Vercel Serverless Function Timeout
Your Vercel serverless functions timeout before completing (504 Gateway Timeout), cutting off long-running operations like data processing, report generation, or large data fetches.
Timeouts occur when functions exceed Vercel's limits (10 seconds for Hobby, 60 seconds for Pro), or when operations are inherently slow.
Error Messages You Might See
Common Causes
- Long-running operations not fitting within timeout limits
- External API calls not timing out, blocking function execution
- Large data processing, image manipulation, or file generation taking too long
- Database queries slow due to missing indexes or N+1 queries
- Not using Vercel's async job queue or background jobs for long tasks
How to Fix It
Upgrade plan: Hobby plan has 10s limit, Pro has 60s. Check plan limits in Vercel docs.
Add timeouts: Set timeout on external calls: const res = await fetch(url, { signal: AbortSignal.timeout(5000) })
Use background jobs: For tasks > 60s, use Vercel's Cron or external job queue (Bull, Inngest).
Optimize queries: Add database indexes, fix N+1 queries, use caching to speed up slow operations.
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Get HelpFrequently Asked Questions
Can I increase the timeout limit?
Hobby: max 10s. Pro: max 60s. To exceed, use background jobs or external processing (e.g., Firebase Cloud Functions).
What should I do for long-running tasks?
Use Vercel Cron for scheduled jobs, or queue library like Bull/Inngest for async tasks that run outside request context.
How do I debug timeout issues?
Add console.log timestamps to find slow sections. Use Vercel Analytics to see function duration. Optimize the slowest part.