Should you are composing a JWT on the fly in a custom function (fn-project) such as the following code in golang:
...
b = fmt.Sprintf("Bearer %s", r.Token) // r.Token is like "eyJ4NXQ..."
log.Print(b)
...
And, apparently, your token looks like fine in the logs as follows:
… is tracing the following entry:
Then, just double check whether the white space in the expression “Bearer %s” is really a white space, because if, for example, it is a tabulator, you’ll get the error mentioned.
Hope this helps!!!
approaching off the bow 