Problem: When your game displays a message box saying "Medieval Engineers cannot be started in 64-bit mode”
Reason: 64-bit version of .NET Framework cannot be loaded
Solution 1: Use the Microsoft .NET Framework Repair Tool
Solution 2: Uninstall all the .NET frameworks from your computer by going to the Control Panel – Uninstall a program and removing all versions of .NET Framework. Then install .NET 4.0 again
Solution 2: Install all Windows updates for .NET and security. Reboot your computer if required by the updates. Then install .NET 4.6.1 again.
Solution 3: Use a 3rd party .NET Framework repair tool. This method will fix any broken .NET configuration.
If you find what is specifically causing this issue, please file a bug here. We’d be happy to create a workaround for Medieval Engineers or provide the tools to fix it automatically.