Can't use Claude Opus 4.5 on opencode using Github Copilot #6281

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1. bhadraagada01

   added

   bugSomething isn't workingSomething isn't working

   on Dec 28, 2025
2. github-actions

   assigned

   rekram1-node

   on Dec 28, 2025
3. github-actions

   added

   windows

   on Dec 28, 2025
4. github-actions commented on Dec 28, 2025

   

   github-actionsBot

   on Dec 28, 2025 – with GitHub Actions

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   This issue might be a duplicate of existing issues. Please check:

   • [aws bedrock: anthropic opus 4.1] The arguments provided to the tool are invalid: Invalid input for tool write: JSON parsing failed: Text #1803: [aws bedrock: anthropic opus 4.1] The arguments provided to the tool are invalid: Invalid input for tool write: JSON parsing failed: Text
   • Incomplete JSON when writing out files #5890: Incomplete JSON when writing out files
   • JSON parsing failed: Text #2188: JSON parsing failed: Text

   All of these report the same JSON parsing error when using the write tool with Claude Opus models (4.1 and 4.5). The error appears to be incomplete JSON being generated with missing closing braces.

   Feel free to ignore if none of these address your specific case.
5. rekram1-node commented on Dec 28, 2025

   

   rekram1-node

   on Dec 28, 2025

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   can u run this and send me file?

   opencode export > session.json
6. bhadraagada01 commented on Dec 29, 2025

   

   bhadraagada01

   on Dec 29, 2025

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   this is only happening when i try with python related project, it works fine with my ts project but ill still give you the session.json

   session-ses_49c3.json
   session-ses_49c3.md
7. aaronkyriesenbach commented on Jan 16, 2026

   

   aaronkyriesenbach

   on Jan 16, 2026

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   I am also running into this issue specifically for Python code - no issues if I work with projects in other languages or specify that the agent shouldn't write any Python code.
8. rekram1-node commented on Jan 16, 2026

   

   rekram1-node

   on Jan 16, 2026

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   @aaronkyriesenbach are u on windows too? Any chance u can send me a session export^^^
9. aaronkyriesenbach commented on Jan 16, 2026

   

   aaronkyriesenbach

   on Jan 16, 2026

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   Nope, tested on both macOS and Linux. Here is a prompt that causes the error on both systems:

   I'm building a deep learning model to denoise audio. I have ~5000 hours of each type, noisy and denoised, and many recordings are of the same content but not synchronized.
   In a previous session, we designed:
   1. An audio pairing pipeline (fingerprinting → coarse alignment via cross-correlation → fine alignment via DTW → quality verification)
   2. A Conformer-UNet generator with attention-gated skip connections operating on complex spectrograms
   3. A multi-scale PatchGAN discriminator
   4. A hybrid training strategy using paired data (supervised losses) and unpaired data (adversarial losses)
   5. A phased training schedule
   Please write a comprehensive markdown guide to `$HOME/audio_enhancement_guide.md` that includes:
   - Complete preprocessing pipeline with technical details
   - Audio pairing and alignment procedures
   - Model architecture specifications
   - Training configuration and loss functions
   - Verification steps to validate preprocessing quality
   - Verification steps to validate training efficacy
   - Evaluation metrics and interpretation
   - Troubleshooting guide
   Make it detailed enough to serve as a complete implementation reference.
   

   And here are the session logs from each system:

   macos_session.json
   linux_session.json

   Updating the above prompt to specify that Python code should not be written results in a successful write:

   In a previous session, we designed:
   1. An audio pairing pipeline (fingerprinting → coarse alignment via cross-correlation → fine alignment via DTW → quality verification)
   2. A Conformer-UNet generator with attention-gated skip connections operating on complex spectrograms
   3. A multi-scale PatchGAN discriminator
   4. A hybrid training strategy using paired data (supervised losses) and unpaired data (adversarial losses)
   5. A phased training schedule
   Please write a comprehensive markdown guide to `$HOME/audio_enhancement_guide.md` that includes:
   - Complete preprocessing pipeline with technical details
   - Audio pairing and alignment procedures
   - Model architecture specifications
   - Training configuration and loss functions
   - Verification steps to validate preprocessing quality
   - Verification steps to validate training efficacy
   - Evaluation metrics and interpretation
   - Troubleshooting guide
   Make it detailed enough to serve as a complete implementation reference. Do not include any Python code in the file.
   

   Here's the successful session:

   working_session.json

   Hopefully this is helpful! Please let me know if there's any other info that I can provide to help troubleshoot. Thanks for your help with this!
10. nalejandroveron commented on Jan 17, 2026

    

    nalejandroveron

    on Jan 17, 2026

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    It seems that the error is always the same, the model forgets to close the JSON? I'm seeing the same now in MacOS python too
11. tyrailleverett commented on Jan 17, 2026

    

    tyrailleverett

    on Jan 17, 2026

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    I am having the same issue with Claude Sonnet 4.5, Claude Haiku 4.5 using Github Copilot. However, I am not using Python. I am getting the error just trying to create a markdown file. I am on the latest opencode and have removed my Github Copilot auth and re-auth. Still same issue. I should point out I am on Mac.
12. tyrailleverett commented on Jan 17, 2026

    

    tyrailleverett

    on Jan 17, 2026

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    Just an update, I came across this issue: #5890, which suggested the error occurs when the model is trying to generate too large of a file, which lines up with the file I was trying to generate. Otherwise, the models work just fine, so it seems when the file is too large (possibly overfilling the smaller context window that Github Copilot provides ) then this error is thrown.
13. EchoCyan commented on Jan 27, 2026

    

    EchoCyan

    on Jan 27, 2026

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    same issue, using github-copilot/claude-opus-4.5 will get endless stuck at preparing write
14. hyperbolic-c commented on Jan 30, 2026

    

    hyperbolic-c

    on Jan 30, 2026

    Last edited by hyperbolic-c

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    same issue, but gpt-5.1-codex work.

    
15. github-actions commented on Mar 31, 2026

    

    github-actionsBot

    on Mar 31, 2026 – with GitHub Actions

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    To stay organized issues are automatically closed after 90 days of no activity. If the issue is still relevant please open a new one.
16. github-actions

    closed this as completedon Mar 31, 2026