Troubleshooting "illegal base64 data at input byte x" Error

time="Aug 12 12:16:37" level=error msg="JWT validation error" api_id=5902527d937a4acc718a8e08b1d492b4 api_name=jwt error="illegal base64 data at input byte 340" mw=AccessRightsCheck org_id=685aa2a5428ba40001dedcb6 origin=192.168.65.1 path=/jwt/anything

This error occurs when the system attempts to decode a Base64-encoded value but encounters invalid or incomplete data, and may be encountered during JWT API authentication.

Possible Causes & Fixes

1. Malformed JWT in Request
   A valid JWT should have three segments separated by periods (.): header.payload.signature
   Use jwt.io to paste and validate the token 
    
2. Malformed JWKS URL in API Definition
   The jwt_source field in the API definition should be Base64-encoded.
   The encoded value must end on a 4-byte boundary; otherwise, it must be padded with = or == at the end of the encoded string.
   Use base64encode.org or the shell command $ echo -n "<jwks-url>" | base64 to encode with correct padding.