The fix for this issue is available in the latest update of InDesign version 15.0.3
Please update your InDesign application to this version to get the fix.
Adobe InDesign team
An error occurred while saving the commentAnonymous commented
I had this same issue and I found the culprit, for me at least. Some of the links a colleague had placed had file path names that were excessively long. I am not sure of the character limit on overall paths or individual file names but I found several ridiculous ones in my document, renamed and resolved the issue.