When you try to join most servers on an Xbox account with a space in it it says invalid name. This needs to be fixed by Maybe replacing the spaces with underscores on sign in. I think this will be a very important bug to fix before the better together update as many people with spaces in their gamertag will be experiencing this issue. And I know thins issue isn't probably going to be marked as a duplicate but I think this is an issue that needs to be more recognised.
Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-11045.
If you have additional information, please add it to that report. If you have not, please search before reporting, as it's likely that one exists already.
Regarding the problem with spaces in gamertags - this is an issue with the software used by third party servers. You might like to contact the server owner directly.
One workaround might be to change your gamertag (to remove spaces):
More information can be found here.
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