Invalid value for ByteString error when calling gmail send API with base64 encoded < or>

Question

Really stuck on this one and pulling my hair out trying to figure out what to do, searched everywhere and tried everything but still stuck. Any help is much appreciated.

Answer 1

The Google API decodes with urlsafe_b64decode. Try to use urlsafe_b64encode (encode strings using a URL-safe alphabet, which uses - instead of + and _ instead of / in the standard Base64 alphabet.)

In your example I see one + which means you used standard Base64.