The fix for this issue is now available in the latest update of InDesign – that is, InDesign 15.0.2.
Please update your InDesign application to get this fix.
Adobe InDesign team
An error occurred while saving the commentAnonymous commented
I'm having the same problem and I'm in the middle of learning InDesign in an adobe class. I have NO undo option or save-as and I'm just just learning this program. Is this really the "top" program of choice for professionals? Because this is pathetic. If I can't fix this I have no choice but to be done with adobe before I even get started.