🔧 Troubleshooting JWT Decoding & Signature Errors
Diagnose malformed token strings, expired timestamps, and invalid signature exceptions.
Example Error & Fix
❌ Malformed Payload
eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiIxMjM0NTY3ODkwIn0
✅ Corrected Payload
eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiIxMjM0NTY3ODkwIn0.signature_hash
💡 Explanation: A valid JWT must contain three dot-separated Base64URL parts: header, payload, and signature.
Common Root Causes
- Token missing one of the three dot-separated segments.
- Token payload contains invalid Base64URL characters.
- Token expiration time ('exp') has passed.
Recommended Solutions
- Ensure the full JWT string with all two dot separators is pasted.
- Check that your authentication server issued a valid RFC 7519 token.
Frequently Asked Questions
Resolve debugging issues faster with these common answers.