League of Legends has its fair share of error codes. One of these is simply known as 0u, an error that typically occurs when using the PBE client. More often than not, the error will cause the home screen (and the rest of the tabs in the client) to display improperly.
Although reporting the error to Riot Support should be your first port of call to help address the issue in future cases, you can also install Hextech Repair Tool. Using this in-house tool, you can siphon out any game errors and patch them up, which then get relayed back to Riot Games for further analysis.
After installing, simply launch the Hextech Repair Tool. Once all of the appropriate boxes have been checked, run the troubleshooter. After the tool has run its diagnostic test, you will be able to amend any possible errors that are causing the 0u error to appear.
Before launching the PBE client, be sure to restart your computer. If the problem persists, you can raise a ticket with Riot Support.
For more League of Legends content, check out How to fix ‘Unable to connect to authentication service’ in League of Legends right here on Pro Game Guides.