Invalid Signature Error
JWT invalid signature error explained. Diagnose wrong secret, algorithm mismatch, and token tampering.
Quick Answer
To fix Invalid Signature Error, decode the token first, check the alg header matches your verification method, confirm the secret or JWKS URL is correct, and validate exp, iss, and aud claims.
Error: Invalid Signature
This error occurs when JWT signature verification fails. The token may have been modified, signed with a different key, or verified with the wrong algorithm or secret.
Quick Fixes
- Confirm the correct secret or public key
- Match the algorithm in the header (alg claim)
- Check for key rotation — use current JWKS kid
- Ensure the token wasn't truncated or modified
Use our JWT Validator to test verification interactively.
Debugging Invalid Signature Error
The error Invalid Signature Error means JWT verification failed. Decode the token, check alg, verify exp is not past, and confirm the secret or JWKS URL matches your auth provider.
Browse related resources: JWT Decoder, JWT Validator, JWT Basics, JWT Authentication, JWT Errors, Algorithms, Glossary, and Learning Path.
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FAQ
What does invalid signature mean?
The cryptographic signature does not match the token content with the provided verification key.