Collecting classes \'utf8' codec can't decode byte 0xa0 in position 12345
If you get this problem, then it probably is due to the fact that your standard temporary directory is somewhere in your user directory…and that might contain non-UTF8 characters. So you can modify your config.json file and insert the following in the top level ‘let’ block:
"TMPDIR" : "c:/temp"
That way you direct the builder to a temp dir which has a valid path.