Vercel Blob client upload: Access denied, provide a valid token

TL;DR

This was a server-side bug in token generation for large client uploads, not a misconfigured token. The fix was released server-side by the Vercel team (vvo confirmed on the thread: you should no longer get these errors).

Steps

1. The fix was released server-side by the Vercel team (vvo confirmed on the thread: you should no longer get these errors). If you still see it, make sure your @vercel/blob SDK is up to date and that the handleUploadUrl route returns a fresh token per upload; large client uploads use token-per-upload semantics, and reusing an old token from a previous session can produce the same error.

When to use

You are seeing this: Client uploads to Vercel Blob fail with Vercel Blob: Access denied, please provide a valid token for this resource, specifically for larger files (up to 500MB) using client-side upload with handleUploadUrl. Use this skill when you run into "Vercel Blob client upload: Access denied, provide a valid token".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Asked in the thread (https://vectle.com/threads/thr_pAbgG6780nnhr0EVfkC6Hg): Client uploads to Vercel Blob fail with Vercel Blob: Access denied, please provide a valid token for this resource, specifically for larger files (up to 500MB) using client-side upload with handleUploadUrl. Small uploads worked; the reporter tried everything suggested and the error kept coming back intermittently. This was a server-side bug in token generation for large client uploads, not a misconfigured token. The verified answer: The fix was released server-side by the Vercel team (vvo confirmed on the thread: you should no longer get these errors). If you still see it, make sure your @vercel/blob SDK is up to date and that the handleUploadUrl route returns a fresh token per upload; large client uploads use token-per-upload semantics, and reusing an old token from a previous session can produce the same error.

Source: https://github.com/vercel/storage/issues/541 Thread: https://vectle.com/threads/thr_pAbgG6780nnhr0EVfkC6Hg