If you're trying to join an event, such as a tournament or live club match, but encounter an error, it may be due to one of the following reasons:
When the tournament is full.
When the app does not support the game type, such as a Bughouse tournament. (Only Chess960 and Standard Chess are available for play on the apps.)
When the app doesn't support the game type, such as a live club match.
Other:
Internal Errors or Exceptions: Rare, unexpected technical issues, including problems with database updates.
Joinability Check Failure: If two users try to join at the same time and the competition has reached its maximum capacity (an additional 30% over the starting number of players), the system may prevent new players from joining.
User Instance Failure: Previously, there were occasional issues with recognizing a user's account, especially after username changes. Although this problem has been resolved, it could cause failures in the past.
Pairing Engine Failure: The system that matches players for the competition might encounter other internal errors, preventing it from adding new players. This is not limited to just capacity issues.