I have the same issue. It crashes when I try to save for web. I get no error message just that 'Operation could not be completed.' And when I try to save png as `save as` I just get a crash report. I have tried that with many different files and the same thing happens.
It will help us to answer your question if you could provide the exact version number you have installed and details of your operating system e.g. • Windows 10 v1809, v1903; MacOS Mojave (10.14) Catalina (10.15) • PSE 2020, PSE 2019 etc You can find this from your application menu: Help >> System Info
Can you save as a Photoshop document (PSD) then re-open the PSD and try: