I noticed PLCnext Engineer versions accumulate with each installation. They are not erased or written over. When older versions are uninstalled, a folder is left in C:/Program Files/Phoenix Contact/PLCnext Engineer 2021.9 as an example. Do we need to leave it or erased it?
You can have multiple versions of PLCnext Engineer installed if you want or (like me) you can uninstall old versions before installing the latest version. After uninstalling an old version, the project files should still be on the PC, so you can open them in the new version of PLCnext Engineer.
It’s not clear why that folder you mentioned is left behind when old versions are uninstalled. It only contains one small dll and can be deleted, if you want.