Unreal Engine Project Won't Open After Upgrade

How to fix it

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

1. 1. Back up first

   1. Copy the whole project folder before converting
   Did this fix it? Yes No

2. 2. Disable incompatible plugins

   Copy steps
   1. Open the .uproject in a text editor and set Enabled: false on suspect plugins (Houdini, marketplace plugins)
   2. Reopen and allow the rebuild
   Did this fix it? Yes No

3. 3. Clean and regenerate

   Copy steps
   1. Delete Binaries and Intermediate (and .vs)
   2. Right-click the .uproject > Generate Visual Studio project files
   Did this fix it? Yes No

4. 4. Build in Visual Studio

   Copy steps
   1. Open the .sln, set Development Editor / Win64, build and read the first error
   2. Fix code errors, then launch the project
   Did this fix it? Yes No

Symptoms

After switching engine versions you see 'The following modules are missing or built with a different engine version' or 'Could not be compiled. Try rebuilding from source manually'.

Why it happens

• Compiled modules built for the old engine version
• A plugin or marketplace asset not updated for the new version
• Code errors that stop the module compiling
• Stale project files

This guide also covers

• unreal engine project won't open after upgrade
• modules are missing or built with a different engine version
• unreal engine could not be compiled try rebuilding from source manually

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 Fatal Error Crash
• Unreal Engine GPU Crashed or D3D Device Removed
• Unreal Engine Shaders Compiling Forever (Stuck at 45%)
• Unreal Engine Out of Video Memory Error
• 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