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FUNCTION_INVOCATION_TIMEOUT (504)

Exact error

504: GATEWAY_TIMEOUT. Code: FUNCTION_INVOCATION_TIMEOUT

What it means

A serverless function ran longer than its allowed maximum duration and was stopped.

Likely causes

• Slow external API or database queries.
• Awaiting a promise that never resolves.
• Doing long jobs (AI generation, scraping, big imports) inside a single request.

How to fix it

1. Find the slow call in the function logs (Vercel dashboard → Logs).

2. Raise the limit for a route within your plan's allowed maximum:

   // app/api/generate/route.ts
   export const maxDuration = 60; // seconds

3. Add timeouts to outbound fetches so they fail fast:

   await fetch(url, { signal: AbortSignal.timeout(10000) });

4. Move long jobs to a background queue/cron, or stream the response.

Prevent this next time

• Add timeouts to outbound requests and return clear error responses instead of crashing.
• Set up uptime checks and log alerts on critical endpoints so you hear about failures before users do.

Guide: catch outages before your users do.

Related errors

• FUNCTION_INVOCATION_FAILED (500)