The application cannot be started. [context="user"] caught unexpected com.sun.star.ucbInteractiveAugmentedIOException:an error occured during file opening. what do I do next?

I have used LibO for many years. Yesterday when I tried to open it I received the following message.-

The application cannot be started.
[context=“user”] caught unexpected
com.sun.star.ucbInteractiveAugmentedIOException:an error occured during file opening

I have tried uninstalling with the aim of reinstalling the latest version but the usual uninstall route says it can’t be done.

Any ideas?