"An unknown error occurred performing that action" when downloading the UEFN in the EGL

If you receive the message "An unknown error occurred performing that action" when trying to download or update the Unreal Editor for Fortnite on the Epic Games Launcher, and you already tried the steps from the article Troubleshooting the Epic Games Launcher, you can try doing a full cache clear via deleting the following folders:

• C:\ProgramData\Epic
• C:\Users\<YourUser>\AppData\Local\EpicGamesLauncher
• C:\Users\<YourUser>\AppData\Local\UnrealEngine
• C:\Users\<YourUser>\AppData\Roaming\Epic
  Note: Enabling hidden files might be needed to see some of these folders.

Deleting these folders will reset all launcher data, so you might need to reinstall your games.