What is the error? See: Corrupt or Otherwise Broken Audacity Project Recovery
Before you do any editing make sure you save a .WAV file backup.
Note that when you do any edits, Audacity saves UNDO information, so it can roll back your change if you decide you don’t want it. But the downside of this is that even a simply amplify operation of say, .01, will double the size of a new project.
When I edit large projects, I save then close the project after every two or three edits.
Alternatively, you can select a smaller chuck of audio, say 1 hour, copy it, then paste it to a new project and work with the new project. Do NOT copy smart clip information.