Common Duolingo English Test Mistakes To Avoid in 2026

Are you worried about spending time and money on the DET, only to have your test invalidated by a technical error?

Many students preparing for the common Duolingo English Test mistakes in 2026 already know the syllabus and format, yet still lose marks or face delays simply because the test is stricter than they expect. 

Since the DET is taken at home, the system pays close attention to your lighting, background, audio, and even small movements. This is where most students run into problems, not because their English is weak but because they overlook how sensitive the review process has become.

The test records everything on your screen and in your room for the entire one-hour session. If the camera cannot see you clearly, the room is dim, or your audio is uneven, the system flags it. 

Students also lose marks when they speak too fast, rush through reading tasks, or submit writing without checking for basic errors. These are everyday mistakes, but they affect your score more than you might think.

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Let’s understand what these mistakes are and how to avoid them while taking DET.

Most invalidations in Duolingo English Test (DET) 2026 come from rule violations flagged by Duolingo’s automated and human review. These issues have nothing to do with English level. They occur when the system cannot confirm identity, room conditions, or test integrity. Here are the most frequent reasons students receive withheld or invalid results.

Frequent glances to the side, down, or off-screen create doubt about what you are referring to. Even brief eye movements can trigger flags during review.

Webcams that are blurry, poorly angled, or linked to virtual-camera tools often lead to invalidation. Using more than one screen or any secondary camera is not allowed.

Any background voices, someone entering the room, or responding to sounds can be seen as external help. Even distant conversations or phone alerts may impact certification.

Tools like Grammarly, VPNs, screen recorders, and active browser extensions are flagged because they can influence answers. DET requires a clean device with no add-ons.

Dim lighting, shadows, and unclear backgrounds make it hard to verify your identity. The camera must clearly see your face and the room at all times.

Traffic, family conversations, construction noise, or open doors can raise concerns. The test must be taken alone in a quiet room.

Even when the test is certified, many students fall short of their target score because of avoidable performance issues. These mistakes come from task habits, pacing, and clarity rather than weak English skills. The DET’s adaptive system rewards precision, relevance, and consistency, so small lapses can immediately affect your score.

Rushing through Interactive Reading, Listening, or Extended Writing often leads to missing key details. Many students answer before fully understanding the prompt, which reduces accuracy.

Memorising random word lists does not help, because the DET tests contextual vocabulary. Guessing widely or relying on pattern tricks leads to score drops.

A short answer limits your ability to show vocabulary range and clear structure. Students who stay near the minimum often score lower, even if grammar is correct.

Going off-topic, adding unnecessary details, or drifting away from the prompt weakens coherence. The system evaluates relevance closely.

Many students start strong but lose direction halfway, especially in longer answers. This reduces both fluency and task completion quality.

Fast speech affects pronunciation, clarity, and intonation. The system needs clean audio to score speaking accurately.

Choosing every word to avoid missing any is a common mistake. Incorrect selections lower the score more than skipping doubtful words.

Missing commas or periods changes the sentence meaning. Even small errors reduce accuracy in Listen and Type tasks.

Skipping a quick review leads to avoidable grammar errors, missing words, and awkward phrasing.

These issues are not technical failures or language mistakes but simple oversights that often affect performance or delay results. Many students only realise them after the test, which makes them important to identify early.

Some students wait too long or assume the test will auto-start recording. If you don’t click the prompt in time, you lose valuable seconds and sometimes the entire response window.

Interactive Reading and Listening include several tasks within one screen. Students often spend too long on one part and rush the rest, lowering accuracy and coherence across the set.

Outdated browsers, blocked permissions, or low battery can interrupt the session. A quick pre-check ensures your device meets Duolingo’s requirements for camera, mic, and system performance.

Taking the practice test casually leads to poor pacing in the real exam. Students who treat the sample as a trial often misjudge time pressure and question difficulty.

When students overthink a question, they often fall silent or restart their structure mid-sentence. Nervous pauses reduce fluency and coherence, especially in speaking tasks.

Technical problems directly influence whether the DET can verify your identity, room conditions, and recorded responses. Duolingo’s review team checks video and audio quality frame by frame, so even small disruptions can affect certification. Below are the specific issues that cause the most problems in 2026 and how to respond to each one.

Small drops under 3 to 5 seconds can cause answer submission delays. Longer outages interrupt recording or prevent the test from uploading. Students on hotspot or shared Wi-Fi face this most often.

Older laptops or devices running heavy apps (Chrome with many tabs, background updaters, antivirus scans) often overheat after 25 to 30 minutes. If the device shuts down mid-test, Duolingo cannot complete the verification process.

Low input volume, background static, or permissions not granted can result in incomplete speaking samples. The system marks these as unusable because scoring requires clear waveform data.

Cameras that flicker, lose focus, or dim automatically during the session cause identity verification gaps. Even brief moments of unclear visibility can trigger additional review.

Browsers that are outdated, unstable, or blocked by extensions can freeze during Interactive Reading or Speaking tasks. This affects timing accuracy and final answer submission.

• When to wait
  If the test freezes for under 10 seconds but resumes on its own, continue without refreshing. Duolingo still captures the recording during short pauses.
• When to contact DET support
  If the upload fails, the recording stops, or the test ends abruptly, submit a support ticket through the Duolingo Help Center with your test time, system logs, and error message.
• When free retests are provided
  Free retests are offered only when system logs show a technical disruption not caused by the student, such as server-side issues or recording failures outside your control.

Most students focus on avoiding errors but overlook what to do instead. These strategies replace common mistakes with clear, high-scoring habits that match how the DET evaluates clarity, relevance, vocabulary range, and task completion in 2026.

Read the prompt twice, identify the main idea, and plan one clear line of argument. For speaking, use a mental outline with a short introduction, one example, and a closing line to maintain direction.

Focus on topic-based vocabulary such as technology, education, travel, and daily routines. Practice using these words in short sentences so the adaptive scoring system recognises natural usage rather than memorised lists.

Use a basic structure: state your main idea, give one example, and explain why it supports your point. This keeps answers focused and prevents drifting away from the prompt.

Use the first 60 to 70 percent of the time to write your full response and keep the last 20 to 30 percent for proofreading grammar, punctuation, and missing words. A short review improves clarity and accuracy.

Set internal checkpoints. For example, spend the first few seconds understanding the prompt, the next half writing or speaking, and the final part reviewing. This prevents rushing and improves structure.

Practice timed responses regularly so the format feels familiar. If you freeze, take a short pause and reset your thoughts. Controlled pacing improves fluency more than trying to speak continuously.

For practical ways to improve your performance in the 2026 test format, you can also check the guide on Proven Duolingo English Test Tips & Tricks to Raise Your Score Fast.

Use this one-page checklist before your test. It covers room setup, device rules, performance habits, and technical readiness so you avoid invalidation and protect your score.

• Test in a private room with the door closed and no one entering.
  
• Keep the lighting bright and even so that your face and background are clearly visible.
  
• Ensure the camera shows your entire face without shadows or angles.
  
• Remove mirrors, reflective surfaces, and clutter behind you.
  
• Keep the room silent and turn off fans, notifications, and background devices.
  

• Use a laptop or desktop with a working webcam, microphone, and speakers.
  
• Disable additional screens, secondary cameras, and virtual-camera tools.
  
• Close all apps, extensions, VPNs, and background updaters.
  
• Update your browser and grant camera and microphone permissions.
  
• Start with at least 50 to 60 percent battery and a charger connected.
  

• Use a stable broadband connection, not hotspots or shared Wi-Fi.
  
• Sit close to the router to reduce drops and lag.
  
• Avoid downloading files, streaming, or multitasking during the test.
  

• Keep your eyes on the screen and avoid frequent head or eye movements.
  
• Speak at a steady pace with clear pronunciation.
  
• Stay relevant to the prompt and avoid adding unrelated ideas.
  
• Do not guess widely in vocabulary tasks.
  
• Use the last few seconds to proofread writing.
  

• Use checkpoints to manage long tasks.
  
• Click “Record Now” immediately during speaking prompts.
  
• Treat the practice test like a real simulation for accuracy.
  
• If the test freezes briefly, wait without refreshing.

If you want a clearer plan for building strong habits before test day, you can also refer to our detailed guide on How to Prepare for Duolingo English Test? It takes you through practice strategies, task-specific drills, and study techniques that support the methods shared in this section.

Most students lose marks or face delays on the DET because of avoidable setup and performance issues. When you follow the rules, maintain a clear room setup, speak at a steady pace, and stay relevant to each prompt, the test becomes straightforward and your score reflects your actual ability. With the right preparation, you can complete the exam smoothly and avoid unnecessary risks.

If you want personalised help with DET preparation, university shortlisting, or application support, you can connect with LeapScholar for guidance tailored to your study plans.