Qwen/Qwen3.5-397B-A17B: system message must be at the beginning #20785

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1. majestichou

   added

   bugSomething isn't workingSomething isn't working

   on Apr 3, 2026
2. github-actions

   assigned

   rekram1-node

   on Apr 3, 2026
3. github-actions

   added

   coreAnything pertaining to core functionality of the application (opencode server stuff)Anything pertaining to core functionality of the application (opencode server stuff)

   on Apr 3, 2026
4. github-actions commented on Apr 3, 2026

   

   github-actionsBot

   on Apr 3, 2026 – with GitHub Actions

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

   • When using the qwen3.5-122b-a10b model (via nvidia provider), the following error is returned: System message must be at the beginning #16560: Same error "System message must be at the beginning" with Qwen3.5 models via a custom/third-party provider
   • Multiple system prompts break Qwen3.5-* models #15059: "Multiple system prompts break Qwen3.5-* models" — the superpowers plugin likely adds an extra system prompt, which triggers this exact error in Qwen models that require system messages to appear only at the start of the conversation
5. alienwaredream commented on Apr 4, 2026

   

   alienwaredream

   on Apr 4, 2026

   Last edited by alienwaredream

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   I am reporting a recurring issue where any Q&A attempt triggers the error:

   "System message must be at the beginning."

   This is happening in my current deployment using OpenCode v1.3.13 with the Qwen3.5-122B-A10B-FP8 model served via vLLM v0.19.0.
6. alienwaredream commented on Apr 6, 2026

   

   alienwaredream

   on Apr 6, 2026

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   I am reporting a recurring issue where any Q&A attempt triggers the error:

   "System message must be at the beginning."

   This is happening in my current deployment using OpenCode v1.3.13 with the Qwen3.5-122B-A10B-FP8 model served via vLLM v0.19.0.

   Updating the superpower plugin to the latest version should resolve the "System message must be at the beginning" error and get everything back to normal.
7. sgmihai commented on Apr 16, 2026

   

   sgmihai

   on Apr 16, 2026

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   Also seeing this with qwen3.6-35b via vllm, in opencode 1.4.6 with omo slim plugin.
8. thdxr

   removed

   bugSomething isn't workingSomething isn't working

   coreAnything pertaining to core functionality of the application (opencode server stuff)Anything pertaining to core functionality of the application (opencode server stuff)

   on May 3, 2026
9. robertoberto commented on May 23, 2026

   

   robertoberto

   on May 23, 2026

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   same underlying bug as #15059. also fires with no plugins installed — opencode's title-generator path emits two role: "system" entries on its own (title-generator prompt + inherited delegation block) on the first call of any session against a Qwen 3.5+ deployment.

   confirmed against Qwen/Qwen3.6-27B and Qwen/Qwen3.6-35B-A3B on vLLM v0.21.0 with opencode v1.14.39, vanilla install. the superpowers/opencode-dcp/llama-server reports are the same path made more visible by extra system fragments, not a separate bug.

   diagnosis, fix snippet, and currently-open PR (#16981) tracked in #15059.

   👍React with 👍2Reacted by Crane Huang and Phạm Hồng Phát
10. github-actions commented on Jul 23, 2026

    

    github-actionsBot

    on Jul 23, 2026 – with GitHub Actions

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    To stay organized issues are automatically closed after 60 days of no activity. If the issue is still relevant please open a new one.
11. github-actions

    closed this as not plannedon Jul 23, 2026