As I say dont have all traceback, but reproduce it is easy,
1. On windows create a new OS user Windows using on name 'ñ' and spaces, example:'carlos cataño'
2. Install tryton 4.0 with the user session
3. Try start Tryton client with this new user.
When user name on Windows OS has special character has "ñ" tryton client crash when user try start the login, example:
c:/users/my name with ñ/documents/...
This is traceback:
File "ntpath.pyc", line 85, in join
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xf1 in position 22: invalid...
the last part of the traceback is no visible because is a sended photo by user, sorry.