OpenCode error
OpenCode: CPU lacks AVX support. Please consider upgrading to a newer CPU
CPU lacks AVX support. Please consider upgrading to a newer CPU.
panic(main thread): Illegal instruction at address 0x4001FB4
oh no: Bun has crashed. This indicates a bug in Bun, not your code.Status: Fixed in releaseLast verified 2 documented fixes4 sources
What it means
The Bun runtime bundled in the OpenCode binary used CPU instructions (AVX) that older CPUs lack, so OpenCode crashed on start. This happened even with the baseline build.
Causes
- A Bun regression in the v1.1.21 baseline build. A maintainer: "Bun bug :/" (#8611).
How to fix it
- Fix 1.
A maintainer: "We will just downgrade bun, that should fix it in next release". Upgrade past v1.1.21.
Terminalopencode upgrade - Fix 2.
Later releases fixed baseline handling. v1.1.64: "Baseline CPU detection fixed" (PR #13371). v1.2.11: "Upgrade to Bun 1.3.10 canary and force baseline builds always".
More OpenCode errors
All 17 OpenCode errorsProviderModelNotFoundErrorStatus: By designProviderInitErrorStatus: WorkaroundAI_APICallErrorStatus: WorkaroundThis credential is only authorized for use with Claude Code and cannot be used for other API requests.Status: By designAI_APICallError: messages.13: `tool_use` ids were found without `tool_result` blocks immediately after: toolu_01CfJCsh21fK1pAXsXWYJYBA, toolu_01NoqnwsaxoK3AYM2FyrxmjN. Each `tool_use` block must have a corresponding `tool_result` block in the next message.Status: Fixed in releasemessages.3.content.0.type: Expected `thinking` or `redacted_thinking`, but found `tool_use`. When `thinking` is enabled, a final `assistant` message must start with a thinking block (preceeding the lastmost set of `tool_use` and `tool_result` blocks). We recommend you include thinking blocks from previous turns. To avoid this requirement, disable `thinking`.Status: WorkaroundError: Unexpected error, check log file at [user-home]/.local/share/opencode/log/2025-08-26T215857.log for more detailsStatus: WorkaroundAI_RetryError: Failed after 4 attempts. Last error: Too Many RequestsStatus: Workaround
Related reading
- OpenCode Hacked: What the Console Breach Means for Your API KeysOpenCode disclosed a breach of its Console that may have exposed provider keys. Who is affected, what to rotate today, and why hosted key gateways are the real risk.
- OpenCode 2: How to Upgrade From v1 Without Breaking Your SetupOpenCode 2 upgrade from v1: what the migration guide says breaks (plugins, server API, TUI config), what carries over, and a safe checklist before you switch.
- Run Your Coding Agent as an API: OpenCode Server on RailwayOpenCode server on Railway: run opencode serve in a container as a password-protected HTTP API with a persistent volume, reachable from any machine or webhook.
- Give Every Agent PR a Live Preview: Railway Environments for AI Pull RequestsRailway preview environments for agent pull requests: an isolated copy of your whole stack for every PR, so you verify agent changes by running them.
- GPT-6 Astra Release Guide: Benchmarks, $10/$50 Pricing, and How to Run It in Codex and OpenCodeGPT-6 Astra release guide: OpenAI's max-capability model, its $10/$50 pricing and 1.05M context, what the benchmarks do and do not say, and commands to try it.
- Put an AI Reviewer on Every Pull Request: A Webhook Build with OpenCode and RailwayBuild an AI pull request reviewer on Railway: a webhook service runs OpenCode headless on every PR diff and posts findings as a review, never touching the code.
FAQ
What does "CPU lacks AVX support. Please consider upgrading to a newer CPU" mean in OpenCode?
The Bun runtime bundled in the OpenCode binary used CPU instructions (AVX) that older CPUs lack, so OpenCode crashed on start. This happened even with the baseline build.
How do I fix "CPU lacks AVX support. Please consider upgrading to a newer CPU"?
There are 2 documented fixes. Start with the first: A maintainer: "We will just downgrade bun, that should fix it in next release". Upgrade past v1.1.21.
Is this OpenCode error fixed?
Status: Fixed in release. A release fixed this. The affected versions note says where the fix landed. Affected versions: v1.1.21-baseline (regression from v1.1.20). Baseline detection fixed in v1.1.64, and baseline builds forced from v1.2.11.
Sources
Last verified against 4 sources: official docs, maintainer replies and release notes.
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