An error occurred while saving the commentPhyllis Bi commented
I reproduced the issue on Adobe Premiere Pro Version 14.3.1 (Build 45), running on Windows 10 Home Version 1909. I ran into this error when I use Project manager to save my project, "an unknown error occurred during the project manager operation. Please save your project and retry the operation.", with "collect files and copy to new location" checked.
The issue is caused by an audio file used in the sequence, this audio file has a single quote in the file name. I believe this error happens when adobe is trying to copy this file to destination location. I was able to verify this cause, by removing the single quote in the source filename.