HTML5 Build Error UnicodeDecodeError: 'ascii'

Thank you for your answer.
I have rebuilt the whole engine including the “Thirdparty libraries”

I also checked over 7 times variable by variable.
There were no weird characters. All what I have typed was (a-z, A-Z, 0-9)
I even had a + and I removed it.
Still the same error.

Is there a possibility to send you privately the blueprints to check it up? or any other suggestions?

Thank you.