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

In Google Apps Script following fixes the issue

var draftBody = Utilities.base64EncodeWebSafe(raw);

Don't use var draftBody = Utilities.base64Encode(raw);