I recently decided to switch my 4.12.3 source project to 4.13.2.
I downloaded the 4.13.2 source, compiled it and switched the project to it but when i try to open it the following error appears.
Everything works correctly if i switch back to 4.12.3.
If i try making a new project from the 4.13.2 editor it will open without any error.
If you were able to create/open a new project in the 4.13 engine, it’s possible that engine code that changed between 4.12 and 4.13 is conflicting with the code in your project. If possible, you may want to try copying your code to a new project in pieces to see if there is a portion that is causing the issue.