After Catalina update files won't save or open on Mac Book

I concur with ria36 that it sounds like a permissions issue. Where are you trying to store these files?

One major thing that changed with Catalina is that most of the disk structure is off-limits for user files. Files and folders should be inside the user home folder or in a limited number of other places. In particular, the root of the system volume is now protected. Catalina installation should have moved user data away from the new protected area.

Have a look here: It's possible you have to change permissions

https://support.apple.com/guide/mac-help/change-permissions-for-files-folders-or-disks-mchlp1203/mac

Please explain your issue in more detail. The only "ifiles" I can find is an app for iOS devices, not Macs. Just where are these files that give you trouble?