If you are trying to play Fortnite on PC and keep getting the “Signature error detected when reading container header” error message (usually after an update). It means the game cannot validate one or more of its digitally signed content containers. Which means you now have to do a ton of random things looking for ways to fix the fortnite error. So follow along as we guide you through all those random solutions.

Takeaways:

  1. Solution for Fortnite error: “Signature Error Detected When Reading Container Header”
  2. Fortnite error after updating: “Signature Error Detected When Reading Container Header”

How to Fix Fortnite “Signature Error Detected When Reading Container Header”

Before you start doing anything else in this guide try this quick fixes first, if you haven't already. Once you have tried these things without any success start the solutions further down.

  • Restart your PC and relaunch the Epic Games Launcher
  • Make sure the drive where Fortnite is installed has enough free space (at least 15 to 30 GB of free space available)

Note: If you are using an external drive, try running or reinstalling the game on an internal SSD External drives can sometimes cause read or write interruptions.

Verify Fortnite Files

This is the quickest and easiest way to solve this problem. It compares your installed files against the official versions on Epic’s servers. Any missing or corrupted files are automatically re-downloaded and the problem should be solved without having to redownload the entire game.

  • Open Epic Games Launcher
  • Click Library in the left sidebar
  • Locate Fortnite and click the three dots next to it
  • Select Manage
  • Click Verify
  • Wait for the process to complete.

I generally restart my computer after doing this as well though it isn't an officially required step.

How to Fix Fortnite “Signature Error Detected When Reading Container Header”

Clear Epic Games Launcher Cache

Even if files are repaired, the launcher may continue flagging a container as invalid so clear the Launcher cache as well.

  • Close Epic Games Launcher completely
  • Right click the system tray icon and choose Exit
  • Open Task Manager and end any remaining EpicGamesLauncher processes
  • Press Win + R
  • Type %localappdata% and press Enter
  • Open the EpicGamesLauncher folder, then open the Saved folder
  • Delete the webcache folder and any webcache_* folders
  • Restart the launcher and try launching Fortnite again. You may need to sign in again after clearing the cache.

Delete Problematic Container Files

If verification keeps failing on the same container, you can force a clean download by removing the packaged content files manually.

IMPORTANT: Only delete files inside the Paks folder. Do not delete folders such as Saved or Config.

  • Open Epic Games Launcher
  • Go to Library
  • Click the three dots next to Fortnite
  • Select Manage
  • Click the folder icon in the Installation section
  • Go to: FortniteGame > Content > Paks
  • Inside this folder, you may see .pak, .sig, .utoc, and .ucas files.

Container files often come in matching pairs such as .utoc and .ucas. If you delete one file, delete its matching partner and any related .sig file to avoid mismatches.

  • Start by deleting the most recently modified large container files. If the error continues, you can delete all files inside the Paks folder as a last resort.

After deleting the files you'll need to do the following:

  • Return to Epic Games Launcher
  • Click Manage next to Fortnite
  • Click Verify
  • The launcher will re-download the missing files automatically.

Reinstall Fortnite

If nothing above worked you're going to have to bite the bullet and reinstall Fortnite on your computer. This time make sure you install it on an SSD with a fair amount of free space for future updates. Otherwise you're probably going to end up in the same situation before to long.