What causes "HTTP 401 Unauthorized"?

Missing Authorization header in the API request Expired JWT or OAuth token Wrong API key or secret Bearer token format is incorrect (e.g., missing 'Bearer ' prefix) Session cookie expired or was cleared

HTTP Error3 Fixes Available

401 Unauthorized — Authentication Required

HTTP 401 Unauthorized

What does this error mean?

A 401 response means the request lacks valid authentication credentials. The server is saying 'I don't know who you are.' Unlike 403, providing valid credentials may grant access.

Common Causes

Missing Authorization header in the API request
Expired JWT or OAuth token
Wrong API key or secret
Bearer token format is incorrect (e.g., missing 'Bearer ' prefix)
Session cookie expired or was cleared

How to Fix It (3 Solutions)

Add the Authorization header

Include the correct Authorization header in your request.

Code

fetch('/api/data', {
  headers: {
    'Authorization': 'Bearer YOUR_TOKEN_HERE',
    'Content-Type': 'application/json',
  }
});

Decode your JWT to check expiry

Use our JWT Decoder to inspect your token's exp claim and see if it has expired.

Refresh your access token

Implement token refresh logic to get a new access token when the current one expires.

Fix this error faster with our free tool

JWT Decoder

Open JWT Decoder

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403 Forbidden — Access Denied

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JsonWebTokenError: jwt expired

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