How do i fix the 'CSG error code'?

-edit- Fixed. For anyone who needs help if there facing a similar problem. Try holding Ctrl+Z (undo) for for about 30 seconds then redo back. Copy-paste the union into another place and see if the particular union is still having a problem.

This is pretty much self explanatory. I lost hours worth of unioning to this… Any solutions?
Desktop_181101_1307

your file may be corrupt. redownload the file and try again.