Duolingo English Test: Technical Setup and How to Avoid Invalidation

DET Ecosystem: Overview

The Duolingo English Test has become a popular choice for high-stakes English testing. It works because it's accessible, fast, and accepted by over 5,000 universities worldwide.¹ But its digital format with AI proctoring creates unique challenges that traditional in-person tests don't have.

Success on the DET requires more than just English skills. You also need to understand the technology and follow strict procedures. This guide covers the DET's technical requirements, how the proctoring works, and the most common mistakes that lead to invalidation. It gives you a practical plan to navigate the system and get your test certified.

Quick Navigation:

• Test Structure
• Proctoring Model
• Technical Requirements
• Identity Verification
• Practice Resources

Test Structure, Duration, and Adaptive Format

The DET is a computer-based exam that tests reading, writing, listening, and speaking skills. It takes about one hour to complete.² The test breaks down into three main parts that walk you through the entire process.

Core Components: The test begins with a 5-minute setup and introduction phase. During this time, the system checks your camera, microphone, and speakers. You submit a photo of your government-issued ID and review all the test rules.³ Then comes the main adaptive test, which lasts about 45 minutes. It uses different question types to measure your English skills.³ The final part is a 10-minute ungraded section with writing and speaking samples. You write a 3-5 minute response and give a 1-3 minute spoken answer. These samples go to institutions along with your score to show your communication skills in action.⁴

How Adaptive Technology Works: The DET uses computer-adaptive testing. This means the difficulty of questions changes based on your answers.⁴ Answer correctly and you get harder questions. Answer wrong and you get easier ones. This helps the system quickly figure out your skill level. You can't just memorize answers because each test is unique and pulls from a large question pool.⁴ Success comes from real language ability, not memorization.

Scoring System: Scores range from 10 to 160, with anything above 120 considered proficient.⁵ You get an overall score plus four subscores: Literacy (reading and writing), Comprehension (listening and reading), Conversation (listening and speaking), and Production (writing and speaking).⁶ This detailed breakdown helps institutions understand your specific strengths and areas for improvement.

Ready to Practice?

Try question types similar to what you'll see on the DET:

• Practice Full Reading Section →
• Practice Writing Questions →

Proctoring Model: AI and Human Review

The DET uses a combination of AI and human review to maintain test security. This hybrid approach provides strong protection for remote testing, though it can feel complex and intimidating.

How the Hybrid System Works: The DET doesn't rely on AI alone. After you finish, an AI system reviews your session for potential rule violations.⁷ Then trained human proctors check the flagged items and make the final decision on certification.⁷ This human oversight separates the DET from fully automated systems. Technology flags issues, but people make the final call.⁸

What Data Gets Recorded: The system captures extensive information during your test. It records video from your webcam and audio from your microphone continuously. A secondary phone camera shows you, your screen, and keyboard.⁹ The system also tracks keyboard and mouse activity.⁹ This comprehensive recording leaves little room for unobserved actions.

How AI Detection Works: The AI looks for unusual patterns in your behavior. It uses statistics, computer vision, and language analysis to check over 75 different factors.⁷ This includes detecting other people in the room, prohibited devices, unusual eye movements, or unnatural speech patterns.⁷ The AI serves as an initial filter, highlighting specific moments for human review.

Invalidation: What It Means and Consequences

Your main goal isn't just a high score. You need a "certified" result that Duolingo officially validates as following all rules. Getting invalidated means your score gets rejected, which can range from needing a retake to permanent bans from the platform.

The remote format with AI creates unique stress. In traditional test centers, you get immediate feedback if you break a rule. With the DET, there's a long delay. Something harmless like glancing up to think, or a family member making noise nearby, can get flagged.¹⁰ You won't know about the violation until up to 48 hours later, and the explanation is often vague.¹¹

This lack of clarity causes a lot of anxiety. The AI acts like a black box, flagging statistical anomalies without understanding intent. A natural behavior like looking away while thinking gets treated the same as cheating.¹⁰ Many people feel this is unfair punishment for normal actions.¹⁰ Some even suspect the system is designed to force retakes for profit.¹⁰

This changes how you prepare. You need to avoid not just cheating, but any behavior that might look suspicious to an algorithm. Preparation includes behavioral training to meet the AI's strict standards. The stakes are high. Duolingo can invalidate results anytime, even after certification, and notify all institutions that received your scores.¹² Severe violations can lead to permanent bans from the DET.¹²

Pro Tip: Read the official rules carefully and practice in front of a mirror to train your test-taking behavior.

Basic Technical Requirements

Meeting the DET's technical requirements is your first step to certification. Problems here are common but completely preventable. The official minimums are just the basics for the test to run. Real user experience shows you need better specs for a smooth experience.

Quick Navigation:

• System Requirements
• Internet Setup
• Camera Configuration
• Software Setup

System Requirements: Supported OS, Hardware, and Unsupported Devices

The DET works on standard desktop and laptop computers. It has specific requirements for operating systems and hardware that you must follow exactly.

Supported Operating Systems: The test app runs only on certain versions of Windows and macOS. Duolingo supports Windows 10 or newer and macOS 10.15 or newer.¹³ Some people claim to use older systems like Windows 7, but Duolingo doesn't support them. Microsoft ended support for Windows 7 in 2020, making it insecure and unreliable.¹⁴ Using unsupported systems increases the risk of compatibility issues and test failure.

Unsupported Platforms: The DET app won't work on several popular devices. Chromebooks, iPads, tablets (including 2-in-1 devices like Surface Pro), and Linux systems are not supported.¹³ Trying to use these will cause the app to fail or crash during the test.

Hardware Requirements: You need a computer with a working webcam, microphone, and speakers.⁴ External USB webcams work if your computer doesn't have a built-in camera.¹⁵ Position the camera at the top center of your screen for best results.¹⁶ Duolingo doesn't list official minimum specs for processor or RAM. Gaming software often specifies these details.¹⁷ Many users report crashes and performance issues with older machines, so use a modern computer with at least 8 GB RAM and a processor capable of video encoding.¹⁸

Test your setup before test day to avoid last-minute issues.

Internet Requirements: Speed, Stability, and Best Practices

A stable internet connection is the most critical technical requirement for the DET. The test uploads multiple data streams simultaneously: two video feeds, audio, and screen recording. Any interruption can corrupt your session and cause permanent failure.

Speed Requirements: Duolingo's official minimum is 2 Mbps download and 1 Mbps upload.¹⁶ Some sources suggest 5 Mbps as a safer minimum.¹⁹ These official numbers are risky. They work only under perfect conditions with no latency or packet loss. Real-world networks vary. A connection meeting minimum specs leaves no safety margin. One bandwidth dip can freeze, end, or fail your test upload, forcing a retake.²⁰ User reports show this happens often. For safety, aim for at least 10 Mbps for both upload and download.

Stability First: Duolingo strongly recommends wired Ethernet over Wi-Fi or mobile hotspots.¹⁶ Wired connections provide steady data flow with less interference or signal drops.²¹

Network Optimization Tips: Maximize your bandwidth and maintain stability with these steps:

1. Disconnect all other devices from your network during the test.²²
2. Ask household members to avoid streaming, gaming, or other high-bandwidth activities.²²
3. Take the test during off-peak hours like late night or early morning to avoid network congestion.²²

Run speed tests from your testing location at the same time you'll take the exam.

Secondary Camera Requirement: Setup, Positioning, and Configuration

A recent DET update requires a secondary camera, and it must be a smartphone.²³ This provides proctors with a second view of your testing environment. Wrong camera setup is a common cause of invalidation.

Phone Setup Steps: Your smartphone must stay charged or plugged in throughout the test.¹⁶ It needs a stable internet connection. Scan the QR code on your computer screen and allow camera access for the DET system.²¹ Enable Do Not Disturb mode to prevent interruptions from calls, messages, or notifications.²³

Positioning Requirements:

1. Place the phone to the side and slightly behind you.
2. Position it so it captures your entire screen, keyboard, and hands without obstruction.²³
3. Use landscape orientation for the best view.
4. Prop it up securely with a heavy object like a book or lamp.²⁴
5. Avoid setups that create blind spots - the whole screen and keyboard must be visible.²³
6. Never touch or move the phone once the test starts.²³

Practice your setup and test the view before test day to ensure everything is visible.

Software and Browser Rules: Clean Testing Environment

The final technical step is ensuring your computer software is completely clean. The DET app is very sensitive to other running programs and will end your session if it detects conflicts.

Supported Browsers: Start your test in an up-to-date web browser. The officially supported options are the latest versions of Chrome, Opera, 360 Browser, and QQ Browser.¹ Outdated or unsupported browsers cause compatibility issues, loading errors, and poor performance.¹⁹

Prohibited Software: The DET strictly forbids other programs during the test.²⁵ This includes messaging apps (WhatsApp, Slack, Telegram), video conferencing tools (Zoom, Teams), grammar checkers (Grammarly), predictive text tools, and remote desktop software (TeamViewer, AnyDesk).²³

Clean Slate Method: Many people get invalidated by hidden background processes they don't even know about, like cloud sync services, software updaters, or antivirus components. Simply closing apps often doesn't stop them. The most effective prevention is a full computer restart right before your test. After restarting, launch only the DET app.²³ This ensures no background processes interfere with your session.

Software Check: Restart your computer and check Task Manager/Activity Monitor to ensure no unnecessary programs are running.

Identity Verification: Global Requirements Matrix

The DET requires strict identity verification during setup. Requirements vary by country, making this a common failure point. Never assume your local ID will work - check the specific rules for your location.

Quick Navigation:

• Universal ID Standards
• Common Rejection Issues
• Country-Specific Requirements

Universal ID Standards: Required Criteria

ID requirements differ by country, but Duolingo sets universal standards that all documents must meet.

Required ID Types:

1. Must be an original, physical government-issued document. No digital versions, photocopies, or handwritten documents allowed.¹⁶
2. Must be valid and not expired on test day.

Required Information:

1. Full legal name (including all middle names and surnames)¹⁹
2. Full date of birth
3. Clear facial photograph
4. Country of issuance
5. Name on DET account must match ID exactly

Special Cases: Duolingo accepts official UNHCR asylum seeker or refugee certificates with the required information: photo, full name, and date of birth.

Common ID Rejections and How to Prevent Them

Most ID rejections happen during photo submission and involve quality issues or mismatched information.

Prevention Tips:

1. Photo Quality: Take ID photos in good lighting with no glare. Use your computer webcam during setup. Make sure the photo is sharp and all text is readable. Laminated IDs often cause glare issues in poor lighting.
2. Recent Photos: If your ID photo is very old and you look significantly different now, proctors may reject it. Keep your ID current.
3. Name Matching: Your DET account name must match your ID exactly. No nicknames, initials, or missing middle names. Double-check before registering.

Verify your name matches exactly and take practice photos to ensure quality.

Regional ID Requirements Matrix

The most confusing part of ID verification is how requirements vary by country. What works in one place might not work in another. This table shows accepted ID types for major regions to help you avoid invalidation.

Key Examples:

• India requires passport only (Aadhaar cards not accepted)
• China explicitly rejects driver's licenses
• Requirements can be counterintuitive, so check your country first

For more detailed guidance on registration and test-taking flow, see our complete guide to the DET process.

AI Proctor: Expected Behavior

Technical setup isn't enough for certification. You also need to follow strict behavior rules during the test. The AI proctoring system detects unusual patterns that might indicate cheating, but it can't understand your intentions. Many normal behaviors get flagged as suspicious, so success requires adopting a specific "test-taking persona."

Quick Navigation:

• Proctoring Sensitivities
• Avoiding AI Flags
• Common Failure Points

Proctoring Sensitivities: Movement, Audio, and Environment

The AI system monitors three main areas: your movements, sounds, and surroundings.

What Gets Flagged:

1. Eye Movement (Most Common Issue): Looking away from the screen for too long is the top reason for invalidation.²⁶ The AI detects any gaze shift from the screen area. This includes normal thinking behaviors like looking up at the ceiling or glancing sideways.²³ Only brief keyboard looks while typing are allowed.²³
2. Sound Detection: Your environment must be completely silent. The microphone picks up any speech or background noise throughout the test.¹⁹ This includes voices from other rooms, music, or TV sounds. Don't speak unless a question requires it.²⁵ Even mumbling or whispering can trigger flags.
3. Room Environment: The testing space has strict requirements. The room needs good lighting so your face stays clearly visible without shadows or glare.²⁷ No other people can be present, even briefly.²³ Clear your desk of all materials, notes, books, and electronic devices.²⁵

Practice in complete silence and train yourself to stay focused on screen.

Automatic Invalidation and Human Review

A human proctor makes the final decision on certification. The type of AI flagged violation often decides the outcome, with some actions classed as "hard fails" that leave little room for interpretation, while others are "soft fails" that depend more on the human reviewer's judgment of the situation.

1. Hard Fails (Likely Automatic Invalidation): These are clear cut violations of key security rules. Examples include another person being clearly seen or heard in the test recording, the test taker speaking to someone off camera, the use of a mobile phone (other than the secondary camera), or the test application detecting that the user has navigated away from the test window.²⁸ In such cases the AI flag is likely to be upheld by the human proctor, and the test will be marked invalid.
2. Soft Fails (Flagged for Human Review): These are more ambiguous behaviors that could be harmless or signs of cheating. Intermittent glances away from the screen, a brief unintelligible background noise, or excessive fidgeting are likely to be flagged by the AI, but a human proctor must review the situation.⁷ The reviewer will look at the duration, frequency, and surrounding circumstances of the flagged behavior to decide if it breaks a rule.

How to Avoid Common AI Flags

Because of the AI's limits, test takers must manage their behavior. They need to give the proctoring system a clear, unambiguous data profile.

1. Gaze Discipline Training: The most important behavioral skill is gaze discipline. Test takers should use the unlimited free practice tests to prepare for content and to train keeping their eyes on the screen, even while thinking.²⁹ Focusing on the question text or a fixed point on the monitor helps build muscle memory and reduces natural but disqualifying eye movements.
2. Environment Sterilization: Treat the testing room as a secure, sterile space. Lock the door before the test. Put a sign outside saying a test is in progress and that interruptions are forbidden. Remove all other electronic devices from the room.
3. The Mirror Technique: Some successful test takers place a large mirror behind the testing station. The primary webcam sees the mirror reflection. This gives proctors a wider, continuous view of the room and its entrances. It can make them more confident that the test taker is alone and the room is secure.
4. Behavioral Rehearsal for Spontaneity: AI and human proctors look for responses that sound rehearsed or pre memorized.¹¹ That creates a problem for test takers who prepare. Practice producing spontaneous answers to many different prompts, not memorized replies. Aim to build fluency and flexibility. On test day your answers should be original, fit the question, and sound natural.

The DET's strict behavioral rules mean success depends not only on English skill but also on a candidate's ability to play a specific, tightly controlled role for the whole exam. The test ends up measuring both language skill and the ability to follow strict AI friendly behavior rules. This changes how people must prepare. Test prep must include a form of "performance coaching." Test takers need training not just in what to say, but in how to act so they are clear and not seen as a threat by the automated proctoring system.

Common Failure Points and Contingency Plans

Even with careful preparation, test-takers can still face problems that threaten the validity of a test session. These problems fall into two main types, technical failures from software or hardware, and procedural issues tied to the appeals process. Knowing the difference and what steps to take helps when handling post-test problems.

Technical Failures: Crashes and Upload Errors

User forums and support threads show a repeated pattern of technical failures that can end a test session suddenly, often without the user doing anything wrong. These problems are not rule violations. They cause a lot of frustration.

1. Common Technical Failures:**Application Freezes or Crashes:** The DET desktop application can freeze or crash without warning during the test. This can force the user to restart the entire session.¹⁸
2. Upload Failure: After the test, the application must upload large recording files to Duolingo's servers. This upload can fail if the internet is unstable. If it fails, the test is lost and the user must retake it.²⁰
3. Loss of Camera/Microphone Access: The application may suddenly lose access to the computer's camera or microphone. That ends the test session immediately.
4. ID Verification Errors: The system may fail to upload or process the user's ID photo correctly. That can stop the test from starting.¹⁸
5. Full-Screen Mode Errors: The application may wrongly detect that the user left full-screen mode, even when they did not. The app then ends the test automatically.¹⁸

Likely Root Causes: Users most often blame unstable internet connections. These explain many freezes and upload failures.²⁰ Reports also point to other causes. Conflicts with background software, like antivirus programs, system services, or screen mirroring utilities on macOS, often cause problems. Also, some hardware and operating system combinations, such as newer MacBooks with M-series processors, show higher rates of these technical issues in user communities.

Infrastructure Challenges and Regional Workarounds

Many test-takers in regions with developing infrastructure, such as parts of Africa, South Asia, and rural Latin America, face unstable internet and unreliable power every day. The DET needs a continuous, stable connection, so it is especially vulnerable in these areas.

1. Addressing Unstable Connections: Mobile Hotspots: Although Duolingo officially discourages the use of mobile hotspots, some users in areas with poor broadband have found that a dedicated 4G or 5G mobile hotspot can provide a more stable connection than shared, low-quality Wi-Fi when the cellular signal is strong and consistent.¹⁶ This remains a high-risk strategy, but it may be the only viable option for some.
2. Off-Peak Testing: Schedule the test late at night or very early in the morning to avoid peak network congestion at home and in the local area. This can lead to a more stable connection.²²

Contingency for Power Outages:

1. Device Power: Make sure both the laptop and the secondary phone are fully charged before the test. Keep both connected to a power source throughout the session.¹⁶
2. Network Power: In regions prone to power outages, a simple power cut will disconnect the internet router and end the test. An uninterruptible power supply (UPS) can provide backup power to a router and modem long enough to complete the test. A UPS is a crucial piece of contingency hardware for at-risk users.

Support and Appeals Process: User Guide

When a test is invalidated, the options to resolve it are narrow and fixed. There is an important difference between invalidations for rule violations and those caused by technical failures. That difference decides what recourse a user has.

1. Eligibility for Appeal: The official appeals process is only for invalidations from suspected rule violations, and only when Duolingo has blocked the user's account or a test credit was immediately used. Invalidations due to technical failures are not eligible for appeal. If a technical issue occurs, the test-taker must use one of their remaining attempts to retake the test.²⁰
2. The 72-Hour Window: For eligible cases, an "Appeal This Result" button appears on the user's results page. You must submit the appeal within 72 hours of getting the invalidation notice. After that time, the button is removed and the chance to appeal is lost permanently.
3. Process and Finality: After submission, a proctoring supervisor or appeals specialist re-examines the test session and the user's explanation. They send a final decision by email within four business days. That decision is final, and only one appeal is allowed per invalid result.

This split system creates a "support chasm." A user flagged for a behavioral issue has a formal, though difficult, way to get a human review that can consider context. By contrast, a user who suffers a real technical failure, like a software crash, has no recourse except to try again. Support for technical issues usually offers generic tips, such as "check your internet connection." Those tips may not fix deeper problems like software conflicts.¹⁸ That forces the user to handle complex technical troubleshooting alone, diagnosing and fixing the issue through costly and stressful trial and error.

Top 20 Pitfalls That Cause Invalidation

This guide pulls together the report's findings into a ranked list of the 20 most common and serious pitfalls that lead to test invalidation. The list uses frequency from user reports and official guidance, plus the severity of each outcome. Each entry gives a description, a step by step prevention protocol, and a contingency plan.

1. Gaze Discipline Failure

Why It Happens:

The AI proctor flags any major eye movement away from the screen as a possible attempt to consult external materials. This is the most common reason for invalidation.²³

Prevention Protocol:

While you practice, train yourself to keep your eyes on the screen even when thinking. Put your monitor at eye level to cut strain. During the test, look at the question text or an empty part of the screen. Short glances at the keyboard while typing are allowed but keep them to a minimum.²³

Contingency Plan:

If you notice you have been looking away, stop and return your gaze to the screen. If the test is invalidated and you are eligible, file an appeal explaining this was a natural thinking habit, not an attempt to cheat.

2. Secondary Camera Misconfiguration

Why It Happens:

The secondary phone camera sits in the wrong spot and creates blind spots. Proctors then lack a full view of the screen, keyboard, and your hands.²³

Prevention Protocol:

Follow Duolingo's official video guide exactly.²⁴ Put the phone sideways to the side and slightly behind you so the whole screen and keyboard are visible. Use a heavy, stable object to hold the phone steady.

Contingency Plan:

If the phone falls or moves during the test, quit the session and restart. The attempt will likely not be counted.²⁴

3. Environmental Contamination (Presence of Others)

Why It Happens:

Another person is seen or heard in the testing room. This breaks the test alone rule and is a serious violation.²³

Prevention Protocol:

Secure your testing space. Lock the door and put a clear TEST IN PROGRESS, DO NOT ENTER sign outside. Tell everyone in your home your test time and stress the need for silence and privacy.

Contingency Plan:

If someone enters, ask them to leave right away and avoid further talk. If the test is invalidated, you can appeal, but it is unlikely to succeed unless the intrusion was extremely brief and clearly accidental.

4. Software Interference

Why It Happens:

The DET app detects another program running in the background, for example a messaging app, grammar checker, or system utility.²³

Prevention Protocol:

Use the Clean Slate method. Restart your computer right before the test. After restarting, open only the DET desktop application.

Contingency Plan:

This is a technical failure and not appealable. You must retake the test after making sure your system is clean.

5. Invalid Identification Document

Why It Happens:

The test taker shows an ID that is not on the approved list for their country, for example using an Aadhaar card in India.

Prevention Protocol:

Before you register, check the Regional ID Requirement Matrix in Section 3 of this report. Make sure your chosen ID is explicitly accepted for your country. When unsure, use a valid, unexpired passport. It is the most widely accepted form of ID.

Contingency Plan:

If your ID is rejected during setup, you will be prompted to resubmit. You will not need to retake the full test. If the problem continues, contact support with a clear photo of your ID to confirm eligibility before trying again.

6. Unstable Internet Connection

Why It Happens:

The internet drops or gets too slow, which causes the test to freeze, crash, or fail to upload.²⁰

Prevention Protocol:

Use a wired Ethernet connection if possible. Test your speed ahead of time and aim for a stable connection well above 10 Mbps. Disconnect other devices from your network during the test.²²

Contingency Plan:

This is a technical failure. You must retake the test. Before you do, fix your connection or use a more reliable location.

7. Poor Lighting Conditions

Why It Happens:

The room is too dark or has strong backlighting, for example from a window. This hides your face and eyes.

Prevention Protocol:

Test in a well lit room. Place the main light in front of you, not behind you. Use a desk lamp to light your face if needed. If you wear glasses, adjust the light to remove glare on the lenses.

Contingency Plan:

If the test is invalidated, this is a rule violation. Retake the test after fixing the lighting.

8. Unsolicited Speaking

Why It Happens:

The test taker speaks when not prompted. They may read questions aloud, think out loud, or whisper to themselves.²⁵

Prevention Protocol:

Practice staying completely silent during the test, except when you must answer a speaking question.

Contingency Plan:

If you are invalidated, this is a rule violation. You may be able to appeal or retake the test.

9. Use of Prohibited Materials

Why It Happens:

The camera detects headphones, earbuds, notes, pens, or other electronic devices in the testing area.²⁵

Prevention Protocol:

Before starting, clear your desk and the area around you. Remove everything except your computer, mouse, keyboard, and secondary phone. Keep your ears visible and uncovered at all times.²⁵

Contingency Plan:

This is a serious rule violation. Depending on severity, your account may be blocked. You may be able to appeal.

10. "Rehearsed" Speaking Responses

Why It Happens:

The AI or a human proctor flags a speaking response as sounding staged, memorized, or read from a script.¹¹

Prevention Protocol:

Practice giving spontaneous answers on many topics. Do not memorize long paragraphs. Use natural intonation and a conversational pace.

Contingency Plan:

This kind of invalidation is hard to win on appeal because it depends on subjective judgment. If your appeal fails, speak more naturally on your retake.

11. Name Mismatch

Why It Happens:

The name on the Duolingo account does not match the name on the ID document exactly.

Prevention Protocol:

When you register, enter your full legal name exactly as it appears on your ID, including given names, middle names, and surnames.

Contingency Plan:

You will likely be asked to correct your registration and resubmit your ID.

12. Secondary Phone Interruption

Why It Happens:

The secondary phone gets a call, message, or notification and interrupts the recording.²³

Prevention Protocol:

Turn on Do Not Disturb or Focus mode on your phone before the test.

Contingency Plan:

The test will be invalidated. You must retake it after you fix your phone settings.

13. Using Multiple Accounts

Why It Happens:

The test taker tries to use more than one Duolingo account, which is not allowed.

Prevention Protocol:

Use only one account for all DET activity.

Contingency Plan:

This is a serious violation. The extra account will likely be blocked and the test invalidated. An appeal might get a refund for the second purchase, but the block will probably remain.

14. Exiting Full Screen Mode

Why It Happens:

The user leaves the test window by mistake or on purpose, or a system error flags an exit from full screen mode.

Prevention Protocol:

Keep your mouse inside the test window. The Clean Slate restart can help prevent pop ups or other apps from taking focus and causing this error.

Contingency Plan:

This error ends the test and cannot be recovered. You must retake it.

15. Insufficient Speaking Duration

Why It Happens:

The test taker does not speak for the minimum required time, for example at least 30 seconds in an open ended speaking section.

Prevention Protocol:

Aim to speak for the full time allowed for each speaking question. Practice expanding your points so the time fills naturally.

Contingency Plan:

This breaks the rules. If invalidated, give longer, more detailed answers on your retake.

16. Expired ID

Why It Happens:

The ID shown is past its expiration date.

Prevention Protocol:

Check your ID's expiration date well before the test. If it is expired or will soon expire, renew it or use another valid ID from the approved list.

Contingency Plan:

The ID will be rejected during setup. You must get a valid ID before you can take the test.

17. Low Microphone Volume

Why It Happens:

The microphone input is too low, so the system cannot grade the speaking parts accurately.

Prevention Protocol:

During setup, the test asks you to speak to check your microphone. Speak clearly at a normal conversational volume. Check your computer settings to make sure the microphone gain is set correctly.

Contingency Plan:

This technical issue leads to invalidation. Before retaking, test your microphone with your computer tools or a third party site to confirm it works.

18. Use of Predictive Text

Why It Happens:

The system detects an input method that uses predictive text or auto complete features.²⁵

Prevention Protocol:

Use a standard system keyboard input method. Turn off any third party input method editors or software with these features before the test.

Contingency Plan:

This is a rule violation. If invalidated, make sure all such software is turned off or uninstalled before your retake.

19. Shared IP Address Flag

Why It Happens:

The test is taken on a public or shared IP address, for example at a test center or university library, that has ties to past fraudulent activity.¹⁰

Prevention Protocol:

The safest choice is to take the test from a private home internet connection. If you must use a shared network, know the risk.

Contingency Plan:

This invalidation can be hard to appeal because Duolingo will not reveal its security flags. Your best option is to retake the test from a different network.

20. Test Credit Expiration

Why It Happens:

The test taker does not complete a certified test within the 21 day validity period of their test credit, or the credit is used up by multiple invalidations.²⁵

Prevention Protocol:

Schedule your first attempt well before the 21 day deadline so you have time for possible retakes. Prepare thoroughly to lower the chance of invalidations that consume your attempts.

Contingency Plan:

If your credit expires, you must buy a new one. In some cases, if an invalidation happens near the end of the 21 day period, support may grant a 7 day extension.

Pre Test Validation Checklists

To put the prevention strategies in this report into action, use the following checklists. They offer a clear, step by step verification process for the final 48 hours before taking the Duolingo English Test. Following these checklists will greatly lower the chance of avoidable failures.

48 Hour Pre Test: System and Document Preparation

This phase makes sure your main software and identification are ready and meet the requirements.

1. Verify Identification: Locate your chosen government-issued photo ID. Check it against the Regional ID Requirement Matrix in Section 3 to confirm it is an accepted type for your country. Make sure it is not expired. Make sure the name on the ID exactly matches the name on your Duolingo account.
2. Update Operating System: Go to your computer's settings and check for system updates. Install any pending updates for your Windows or macOS operating system to get the latest security patches and compatibility fixes.
3. Update Web Browser: Open your main browser. Chrome is recommended. Check for updates. Make sure you are running the latest version to avoid compatibility issues during the test.¹⁹
4. Install/Update DET Application: Go to the official Duolingo English Test website and download the latest desktop application. If you already have it installed, uninstall the old version first. Then install the new version so you have all recent updates and bug fixes.
5. Conduct Baseline Internet Test: Run an internet speed test from the spot where you will take the test. Make sure your connection is stable and consistently provides speeds well above the recommended baseline. Aim for at least 10 Mbps download and 10 Mbps upload. If the speed is insufficient, make other plans, for example arranging a wired connection.²²

24 Hour Pre Test: Environment and Connectivity Lockdown

This phase prepares your room and network to create a secure, stable testing environment.

1. Select and Secure Testing Room: Choose a quiet, private room where you will not be disturbed. Tell family members, roommates, or colleagues your test schedule and enforce a strict "no interruptions" rule.
2. Prepare the Physical Space: Clear your desk of all materials, including papers, books, pens, and all electronic devices (except for the computer, monitor, keyboard, mouse, and secondary phone). Make sure the background behind you is simple and uncluttered.
3. Test Lighting Conditions: Sit in your testing chair and open your webcam. Check the video feed so your face is clear and evenly lit. Remove strong backlighting from windows or lamps. If needed, place a desk lamp in front of you to light your face and prevent shadows. If you wear glasses, remove any glare on the lenses.
4. Prepare Wired Connection: If you have an Ethernet cable, plug it into your computer and router, then test the connection to make sure it works. A wired connection is strongly preferred for stability.²¹

1 Hour Before Test: Final Equipment and Environment Sweep

This is the final preparation step before the pre-launch lockdown.

1. Post "Do Not Disturb" Sign: Place a clear sign on the outside of your locked door that reads "TEST IN PROGRESS, DO NOT ENTER".
2. Charge and Connect Devices: Ensure your laptop and secondary phone are fully charged. Plug both devices into a reliable power source. Leave them plugged in for the entire test.¹⁶
3. Prepare ID and Phone Stand: Place your physical ID document on the desk, ready for the verification step. Position the heavy object, such as a stack of books, to prop up your phone.²⁴
4. Final Practice Test: Take one last short practice test. Use it to check that your camera, microphone, speakers, and internet connection all work properly in the test environment.²⁹ This also serves as a mental warm-up.

5 Minutes Before Test: Final System and Rule Verification

This is the final, important lockdown sequence. Perform these steps immediately before you begin the test.

1. RESTART THE COMPUTER: This is the most important step to make sure no unauthorized background processes are running. Shut down your computer completely and turn it back on.
2. Launch Only the DET App: After the restart, do not open any other programs. Launch only the Duolingo English Test desktop application.
3. Isolate the Network: Disconnect all other devices (phones, tablets, etc.) from your Wi-Fi or local network.
4. Lock the Door: Physically lock the door to your testing room.
5. Set Phone to "Do Not Disturb": Enable "Do Not Disturb" or an equivalent "Focus" mode on your secondary phone to block all calls and notifications.²¹
6. Begin the Test: Start the onboarding process and follow all on screen instructions carefully.

Practice Resources

Ready to prepare for the DET? Start with these interactive practice exercises, then explore our full preparation guides:

Interactive Practice Exercises

Complete Practice Sections

• Full Reading Practice →
• Full Listening Practice →
• Full Speaking Practice →
• Full Writing Practice →

Preparation Guides

• Complete DET Guide →
• From Registration to Results →
• Interactive Deep Dive →
• Step-by-Step Process →

Technical Setup Checklist

Use our pre-test validation checklists to ensure everything is ready.

Works cited