Vercel 413 FUNCTION_PAYLOAD_TOO_LARGE (4.5 MB Limit)

Symptoms

File uploads or large API responses fail with '413: Request Entity Too Large' / FUNCTION_PAYLOAD_TOO_LARGE.

Why it happens

• Uploading files through an API route or server action
• Returning large JSON or files from a function
• Proxying downloads through the function instead of linking to storage

How to fix it

Try these in order — the most common fix is first.

1. 1. Upload directly to storage

   1. Use @vercel/blob/client upload() with a handleUploadUrl route, or a presigned S3/R2 URL
   2. Authenticate users in onBeforeGenerateToken
   3. Save the resulting URL in onUploadCompleted

2. 2. Shrink or stream responses

   1. Paginate or return fewer fields
   2. Stream the response; streaming functions are not subject to the limit
   3. Measure size with curl -w '%{size_download}'

3. 3. Serve big files from storage

   1. Return a link or signed URL to the file instead of the file itself

This guide also covers

• vercel 413 payload too large
• function_payload_too_large
• vercel file upload limit
• vercel 4.5mb limit

Other Vercel errors

• Vercel Deployment Failed: Build Error
• Vercel 404 NOT_FOUND After Deploy
• Vercel FUNCTION_INVOCATION_TIMEOUT (504) Error
• Vercel Build Exceeded Memory (SIGKILL / Out of Memory)
• Vercel Environment Variables Not Working (Undefined)
• Vercel Domain Not Verifying (Invalid Configuration)
• Vercel Unexpected Bill: Why Usage Charges Spiked
• Vercel Deployment Blocked: Commit Author Does Not Have Access
• Vercel Not Deploying After Git Push
• Vercel ERR_TOO_MANY_REDIRECTS With Cloudflare
• Vercel 500 FUNCTION_INVOCATION_FAILED Error
• Vercel Project Paused or Account Blocked