When trying to join servers on windows 10 edition, if your gamertag for xbox has spaces, you cannot join as a error message will say, 'Invalid Name'. The only way to change your name in Win10 is to change your Xbox Live ID, which costs money each time you change it.

Another effect of this bug: you may have a correctly formatted gamertag/name but someone on iOS or Android is using that name on a server you want to join and you cannot play because a server will not accept 2 platers with the same name. (Aside: I feel bad for the Xbox Live user who's gamertag is Steve).

In a worst case scenario, griefers could exploit this to keep specific Xbox Live users out of servers by intentionally changing to the mark's name when the mark leaves the server.

COMMENT by MissMarzenia
Unfortunately there is nothing we can do about this issue. Anyone trying to use a server that is not supported by us may run into this issue. Please read comments below for more detailed information.