VS Code Claude Haiku Integration Fails with 'Error during execution'

What this error means

Error during execution — Claude Haiku model fails in VS Code Copilot Chat extension is a VS Code / Claude Code failure pattern reported for developers trying to fix claude haiku model showing ‘error during execution’ in vs code copilot chat extension. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

VS Code issue #305440: Claude Haiku 4.5 model returns ‘Error: Error during execution’ in VS Code Copilot Chat extension (v0.41.1). The ClaudeAgentManager initializes the session successfully, Claude Code SDK starts query processing, but execution fails. The logs show session reuse and CLAUDE.md tracking working correctly before the failure.

Common causes

• VS Code’s integrated Claude agent support (via the Copilot Chat extension, v0.41.1) fails when using the Claude Haiku 4.5 model, showing a generic ‘Error during execution’ message. The session initializes and connects to Claude Code SDK, but the actual query execution fails. This blocks developers who prefer Haiku for its speed and lower cost within the VS Code environment.
• VS Code issue #305440: Claude Haiku 4.5 model returns ‘Error: Error during execution’ in VS Code Copilot Chat extension (v0.41.1). The ClaudeAgentManager initializes the session successfully, Claude Code SDK starts query processing, but execution fails. The logs show session reuse and CLAUDE.md tracking working correctly before the failure.

Quick fixes

1. Confirm the exact error signature matches Error during execution — Claude Haiku model fails in VS Code Copilot Chat extension.
2. Check the VS Code / Claude Code account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/microsoft/vscode/issues/305440

Evidence note: VS Code issue #305440: Claude Haiku 4.5 model returns ‘Error: Error during execution’ in VS Code Copilot Chat extension (v0.41.1). The ClaudeAgentManager initializes the session successfully, Claude Code SDK starts query processing, but execution fails. The logs show session reuse and CLAUDE.md tracking working correctly before the failure.

Related errors

• VS Code Claude agent execution failure
• Claude Haiku model not working in VS Code
• Copilot Chat extension Claude integration error

FAQ

What should I check first?

Start with the exact Error during execution — Claude Haiku model fails in VS Code Copilot Chat extension text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed VS Code / Claude Code workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without Error during execution — Claude Haiku model fails in VS Code Copilot Chat extension.