Unreal Engine Fatal Error Crash

How to fix it

Try these in order — the most common fix is first.

1. 1. Read the log and callstack

   Copy steps
   1. Open <Project>/Saved/Logs and open the newest .log file
   2. Search for 'Fatal error', 'Assertion failed' and 'Access violation'
   3. Note the source file name and any /Game/... asset path, then search that exact text on the Unreal forums
   Did this fix it? Yes No

2. 2. Remove recent changes

   Copy steps
   1. Disable plugins added recently in Edit > Plugins (or set Enabled false in the .uproject)
   2. Reopen the project; if it works, re-enable plugins one at a time
   Did this fix it? Yes No

3. 3. Clear generated folders

   Copy steps
   1. Close the editor and back up the project
   2. Delete Intermediate and Saved/Autosaves, keep Content and Config
   3. Regenerate project files from the .uproject right-click menu and reopen
   Did this fix it? Yes No

4. 4. Update drivers and the engine

   Copy steps
   1. Install the latest GPU driver
   2. Update to the newest hotfix of your engine version via the Epic Games Launcher
   Did this fix it? Yes No

Symptoms

The editor or packaged game closes with a Crash Reporter window titled 'Unreal Engine is exiting due to Fatal error' or 'Assertion failed', often naming a source file and line.

Why it happens

• Corrupted or engine-version-incompatible asset
• Plugin or marketplace content built for another engine version
• Driver or GPU problem
• Stale Derived Data Cache or shader cache
• Engine bug in a specific version

This guide also covers

• unreal engine fatal error
• unreal engine crash
• unreal engine assertion failed
• unreal editor keeps crashing

The same problem in other apps

All crashes, freezes & blank screens guides →

• Unity Hub Not Opening (Unity)
• How to Recover Unsaved or Crashed Blender Files (Blender)

Other Unreal Engine errors

• Unreal Engine GPU Crashed or D3D Device Removed
• Unreal Engine Shaders Compiling Forever (Stuck at 45%)
• Unreal Engine Out of Video Memory Error
• Unreal Engine Project Won't Open After Upgrade
• Epic Games Launcher Stuck Installing Unreal Engine
• Unreal Engine Packaging Failed (Unknown Cook Failure)
• Unreal Engine Visual Studio C++ Build Errors
• Unreal Engine 5 Lumen and Nanite Low FPS