The League of Legends friends list bug prevents you from inviting friends to games. The bug makes it so the friends list is inaccessible. Here's how you can fix this problem.
League of Legends Friends List Bug
Riot Games is aware of the issue. According to Riot Games Support, the blank friend list can be fixed by deleting the Riot Client and League of Legends folders and then reinstalling. They also recommend synchronizing your computer's system clock.
Some users on the official forums have found success by deleting the Riot Client and launching League of Legends from the .exe file itself, using the original log-in screen. There have been a few problems with this new client, with issues ranging from log-in troubles and username logistics. Riot has been fixing the issues that come with the new client as they come up.
League of Legends Patch 10.3 went live earlier this week, bringing plenty of balance adjustments to the game. In the wake of the changes, Riot Games identified Akali and Yuumi as needing further buffs. The developer announced a hotfix Friday that would be applied in the near future, but declined to share a timetable for its release. The hotfix has yet to hit live servers.