Pages Document 'could not be opened'

Possibly important pieces of information:

What version of Pages? (Pages menu > About Pages)

What version of OS X or macOS (Apple menu > About this Mac)

When posting questions, the second should be in your equipment profile, the first in your post.

Assuming macOS 10.15 Catalina and Pages 8.2:

Try a restart of the computer. If that does not cure the issue, try a restart into Safe Mode.

To restart into Safe mode, choose Restart from the Apple menu, immediately on hearing the restart chime press Shift. Keep Shift pressed until you see the log in screen.

In Safe mode, try launching Pages and opening one of the problem documents.

Restart the Mac in Normal mode using Restart in the Apple menu, and this time pressing no keys until you see the log in screen (or your default window if you log in automatically).

Further information on safe mode.

Regards,

Barry

I'm on ac OS X 10.14.6

Pages 8.2.1 & Numbers 6.2.1

Im getting this regularly and it is becoming annoying. I've noticed it happens then you've made a change to the document, but then decide to close it and nat save the newer version, reverting to the original. The original having been created on this version of Pages. I'm pretty certain it does it at other times as well though. These issues should not happen on Apples document applications. I've reinstalled the applications, deleted caches, and everything else suggested but to no avail. The only thing that sees to overcome it, after reinstalling the application is to copy a back up file across. This method of working does not install you with any sort of confidence in Pages and Numbers!