What does the error message "golang illegal base64 data at input byte" mean?

edit

This error message means that the input data being passed to a base64 encoding or decoding function in the Golang programming language is not a valid base64 data, and therefore cannot be processed. The specific byte causing the error may be indicated in the error message. Possible reasons for this error include incorrect encoding or decoding of the data, invalid characters in the data, or truncation or corruption of the data.