Unable to open a file from network with LibrOffice 7.5.3 in Ubuntu linux

For a period of time I had 2 versions of LibrOffice in Ubuntu linux: 7.5.3. and an older one , I think it was a Version 6 release.
When clicking a remote file on a network drive with the linux “files” it opened with version 6 with no problem.
Recently Version 6 has been removed by Linux automatically .
Now, when I click a remote file on a network drive no matter what suffix .docx or .xlsx, a popup appeares, saying " Document in use, This file has been locked by another user" .
I am sure the documents are not in use for I am the only user in my home system.
Is there anybody who has a clue?

When opening a document, LibreOffice also opens a so-called lock file. This is to prevent that two users can access and change a document at the same time.
Check if there is such a file left in the network storage (by abort or other). If LibreOffice is closed, delete this file.

Lock file