Why Vercel triggers 508 INFINITE_LOOP_DETECTED on recursive Nuxt API calls

Problem

A Nuxt API endpoint performs a long-running task. It begins work, and after 5 minutes, it saves the current state and calls its own HTTP route a second time so a new handler instance can resume work on the saved state.

Each handler is guaranteed to run at least 10 seconds.
At most 5 nested calls are made.
After that, the entire task is marked as FAILED and no further nested calls are made.

This causes Vercel to throw a 508 INFINITE_LOOP_DETECTED error after the 4th run:

Screenshot 2026-04-01 at 13.45.03

Question

I’d like to understand how exactly this error is detected. Because, when the individual handlers run the full 5 minutes, the error is now thrown, suggesting there’s some minimum duration they have to run to not being labeled as a loop. If I knew what that lower duration threshold was, I can delay execution to avoid a false positive.

Thank you very much for any help!

Have you had a look at these docs?

https://vercel.com/docs/errors/INFINITE_LOOP_DETECTED

To troubleshoot this error, follow these steps:

Check the application's source code: Look for any code that might cause an infinite loop, such as a looping fetch or an unconditional redirect

Check the application's configuration: Review any configuration files, such as next.config.js or vercel.json, to ensure they are not causing the infinite loop

Review external API or database calls: Ensure that any external API or database calls your application is making do not have errors or infinite loops

Handle unhandled exceptions: Check the application logs for any unhandled exceptions that might be causing the infinite loop

Use Vercel's status page: If you have tried the steps above and are still experiencing the error, check Vercel's status page for any reported outages in the CDN, which can sometimes cause this error

If you're using an LLM, you can also use the following prompt:

1I'm encountering an error and reviewing the docs at https://vercel.com/docs/errors/INFINITE_LOOP_DETECTED.md to understand what's happening.23Please help me resolve this by:451. **Suggest the fix**: Analyze my codebase context and propose what needs to be changed to resolve this error. If you do not have access to my codebase, ask me for the codebase and try to fix the error based on the information you have.62. **Explain the root cause**: Break down why this error occurred:7   - What was the code actually doing vs. what it needed to do?8   - What conditions triggered this specific error?9   - What misconception or oversight led to this?103. **Teach the concept**: Help me understand the underlying principle:11   - Why does this error exist and what is it protecting me from?12   - What's the correct mental model for this concept?13   - How does this fit into the broader framework/language design?144. **Show warning signs**: Help me recognize this pattern in the future:15   - What should I look out for that might cause this again?16   - Are there similar mistakes I might make in related scenarios?17   - What code smells or patterns indicate this issue?185. **Discuss alternatives**: Explain if there are different valid approaches and their trade-offs1920My goal is to fix the immediate issue while building lasting understanding so I can avoid and resolve similar errors independently in the future.