Fix: avast Blocking League of Legends
Avast blocking League of Legends usually means the game launcher won’t open, or important files like LoLPatcherUx.exe are marked as threats and moved to quarantine. This happens when Avast’s real-time protection mistakenly thinks key League of Legends files are dangerous.
The most common reason is a false alarm from Avast’s antivirus or behavior shield, especially after the game or Riot Vanguard updates. Sometimes, old virus definitions or Avast’s anti-exploit features can also interfere with the game files.
Open Your Avast Antivirus
You should be able to access your antivirus easily. If it’s already running, you can find the Avast icon on your taskbar, right-click it, and select “Open.” If Avast does not start automatically, you can manually launch it by locating it in your Start menu. On Windows 10, all programs are listed alphabetically, so Avast should be near the top. Simply click on it and wait for it to load, which might take a few moments. Alternatively, you can double-click the Avast shortcut on your desktop if you have one.

Locating League of Legends Files
It’s possible that Avast has mistakenly quarantined some core League of Legends files, thinking they were viruses. This could be why the game client won’t launch. Luckily, fixing this is straightforward. In Avast, navigate to **Scan → Scan for Viruses → Quarantine (Virus Chest)**. The Quarantine option is usually found at the bottom of the page. When you open Quarantine, look for any files related to League of Legends. If you see them, restore these files and then choose “Add to Exclusions.” If the game has already created new versions of these files, select “Overwrite” to replace them with the originals. After restoring and excluding the files, try launching the game again.

Another Solution
If restoring quarantined files did not solve the issue, or if you didn’t find any League of Legends files in Quarantine, Avast might still be affecting the game in another way. It’s possible Avast continues to report false positives related to League of Legends, blocking the game from launching, even if it hasn’t quarantined any files. Here’s what you can do:
Open Avast Antivirus using any of the methods mentioned earlier. Go to **Settings → Exclusions**. In this section, you can specify files or folders that Avast should ignore during its scans. **Only add files or folders here if you are certain they are safe.** Locate your League of Legends folder (usually found in the Riot Games directory) and add it to the exclusions list. Once you’ve done this, close the Avast window.
Next, right-click the Avast icon on your toolbar and reset the shields by turning them off and back on. This refreshes Avast’s settings, and your issue should now be resolved.
If you follow these steps, League of Legends should launch without interference from Avast Antivirus.