If you are launching Fortnite and getting hit with a Pak is Invalid or SignatureError message before you even get into the game, you are not alone. Epic Games has acknowledged the issue and confirmed its team is investigating it. In the meantime, there are a few steps you can take to fix the Fortnite Pak Is Invalid Error.

What Is the Pak Is Invalid Error in Fortnite

The SignatureError Pak Is Invalid error means that one or more of Fortnite's core asset files have become corrupted or are missing entirely. These files handle things like maps, sounds, and character models, and when they are damaged the game cannot verify them on launch and throws the error instead of loading. It is not caused by anything you did wrong and does not indicate a problem with your account. The files simply need to be located and replaced.

How to Fix the Fortnite Pak Is Invalid Error

Step 1: Verify your game files

  • Open the Epic Games Launcher and go to your Library
  • Find Fortnite and click the three dot menu
  • Select Manage then hit Verify
  • This scans your installation and replaces any corrupted or missing files automatically

Step 2: Delete the FortniteGame folder from Local App Data

Before doing this, take a screenshot of your in-game settings since this process may reset them.

  • Close both Fortnite and the Epic Games Launcher completely
  • Press Windows key + R to open the Run window
  • Type %localappdata% and hit enter
  • Find the FortniteGame folder, right-click it, and select Delete
  • Restart your computer
  • Right-click the Epic Games Launcher and select Run as Administrator
  • Go to your Library, find Fortnite, click the three dot menu, select Manage, and run Verify before launching

Step 3: Reinstall Fortnite

  • Uninstall Fortnite through the Epic Games Launcher
  • Reinstall it fresh to remove any remaining corrupted data the verify process may have missed

Epic is actively investigating the root cause so a broader fix may roll out through an update. If none of the steps above work, keep an eye on the Fortnite Status account on X for updates on when a permanent solution is deployed. You can also look at our Fortnite Server status article as we keep it updated, so bookmarking that page is also a good option!