Request you to share more info on how you are trying to copy paste move assets in Bridge and the observations. This will help us share a resolution accordingly.
An error occurred while saving the commentSotiris A. commented
In the last couple of days, I have the following issue. Firstly appeared when I tried to export from output a pdf of a selection of pictures. Then when I tried to move some files from one folder to another again it appeared. I tried to just copy them and again! Its ays that the files cannot be copied or moved because the file is no longer available. This happened with different files each time.