Cursor API Invalid Request — messages Field Required

What this error means

Invalid request: [{"code":"invalid_type","expected":"array","received":"undefined","path":["messages"],"message":"Required"}] is a Cursor failure pattern reported for developers trying to fix cursor ide api invalid request error when messages field is undefined. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Real error log from Cursor IDE showing Zod validation failure when messages array is undefined in API request. Affects developers using proxy setups with Cursor.

Common causes

• Developers integrating Cursor with custom API proxies or custom LLM backends encounter this validation error when the proxy fails to properly forward the messages array. The Zod validation error is technical and unhelpful for IDE users.
• Real error log from Cursor IDE showing Zod validation failure when messages array is undefined in API request. Affects developers using proxy setups with Cursor.

Quick fixes

1. Confirm the exact error signature matches Invalid request: [{"code":"invalid_type","expected":"array","received":"undefined","path":["messages"],"message":"Required"}].
2. Check the Cursor 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/icebear0828/codex-proxy/issues/507

Evidence note: Real error log from Cursor IDE showing Zod validation failure when messages array is undefined in API request. Affects developers using proxy setups with Cursor.

Related errors

• Cursor custom API proxy configuration
• Cursor IDE OpenAI API compatibility error
• Cursor model endpoint connection error

FAQ

What should I check first?

Start with the exact Invalid request: [{"code":"invalid_type","expected":"array","received":"undefined","path":["messages"],"message":"Required"}] text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Cursor 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 Invalid request: [{"code":"invalid_type","expected":"array","received":"undefined","path":["messages"],"message":"Required"}].