Every time I attempt to load up Halo 5 I’m met with a long wait just for the red and black banner saying “Profile Sync Error”. I’ve restarted the game several dozen times and it keeps happening and have also reset my Xbox One. Basically you can’t do anything if this error occurs, is this on my end or server side? And if it is on my end how can I fix it?
There is a thread pinned at the top of the Halo 5 Support Forum (previous page) for discussing server related problems. You are likely to get more responses from there.
Most of the time any one-off problems with the servers can be solved by just waiting for them to clear up themselves, or by completing a cold reset of your Xbox One. To perform a cold reset, hold down the power button (Xbox logo on the front of your console) for 10 seconds. Additionally, I sometimes find resetting Alternate MAC Address in network settings on your console can make the game a lot more responsive.
Server Discussion Thread:
There was a server issue a few hours ago which should be resolved now.