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NO_RESPONSE_FROM_FUNCTION

Last updated November 25, 2025

The error occurs when a function invocation completes without returning a response. This might happen if the function encounters an error that prevents it from responding, or if it fails to generate a response within the allowed execution time.

Potential causes include:

  • A global uncaught exception
  • A global unhandled rejection
  • A deployment that introduced incorrect syntax
502

NO_RESPONSE_FROM_FUNCTION:

Bad Gateway

Troubleshoot

I'm encountering an error and reviewing the docs at /flg~eyJhbGciOiJIUzI1NiJ9._v7-_v79_g.IN_1YP9lSd3iAlrWfWlSjd7w2BXkRLu_kcJ1imlrEiA/docs/errors/NO_RESPONSE_FROM_FUNCTION to understand what's happening. Please help me resolve this by: 1. **Suggest the fix**: Analyze my codebase context and propose what needs to be changed to resolve this error 2. **Explain the root cause**: Break down why this error occurred: - What was the code actually doing vs. what it needed to do? - What conditions triggered this specific error? - What misconception or oversight led to this? 3. **Teach the concept**: Help me understand the underlying principle: - Why does this error exist and what is it protecting me from? - What's the correct mental model for this concept? - How does this fit into the broader framework/language design? 4. **Show warning signs**: Help me recognize this pattern in the future: - What should I look out for that might cause this again? - Are there similar mistakes I might make in related scenarios? - What code smells or patterns indicate this issue? 5. **Discuss alternatives**: Explain if there are different valid approaches and their trade-offs My goal is to fix the immediate issue while building lasting understanding so I can avoid and resolve similar errors independently in the future.

To troubleshoot this error, follow these steps:

  1. Verify return statements: Ensure that the function has the necessary return statements to generate a response
  2. Check the function logs: Open the realtime request logs for the application in a separate tab - this tab must be kept open while reproducing the error
  3. Review realtime logs: Repeat the application behavior that led to the error being thrown and review the realtime request logs where it will now show
    • Use the information contained within the error logs to understand where the function is failing
  4. Use Log Drains: Create a Log Drain if you do not have one yet, to persist errors from Vercel functions
  5. Check external dependencies: If the function relies on external services or APIs, ensure they are responding in a timely manner

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