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 also experiencing this issue as of yesterday. It just started happening out of the blue!.
When I Command S the file doesn't save and when using command Z the document reverts back to the original opened file with all work done in between lost.
I have now upgraded to 15.1.3 and still no fix.
This is very frustrating and costing me valuable time!!!!
Using macOS Catalina 10.15.7