Is this the bug with the "load error" popup? There has been a lot of discussion on what could be causing it, as well as suggested workarounds, but I don't know of any solutions that work consistently for everyone. One common suggestion I've read is that it could be caused by assets being written into memory too slowly, and that it could be resolved by moving the game to a faster drive (ideally an internal SSD), but that's not a solution for people who don't have an SSD. Alternatively, you can try setting the texture quality to the lowest setting before loading so the game doesn't need to copy as much data.
However, even players with internal SSDs sometimes have this problem, and mechanical drivers are officially supported, so they shouldn't cause problems.
Are you having trouble with a specific save file or every single one of them?