Can't open docx documents

Hello Oleg
What I am doing now is saving a copy of each document in a file equal to the one that I add the word “_copy.docx”
It’s more laborious, but this way I try to avoid losing the data if the file ever becomes unusable.

Hello Barth!
Thank you for you message and a tip. The problem is the file recovery.
I spend some time creating it and now I have to start the work again.
I am frustrated by the inconsistency of OnlyOffice. It happen not first time: I work on a file for a few days every day saving it to receive “The file is corrupt” or “The format is not supported”. Before OF I use Apache with the same outcome.

Hello again, I had this problem also in another word processor, so it seems that it is not a specific issue of OnlyOffice. Even so, a very kind person from OnlyOffice service was attentive to the problem, for which I am very grateful to OnlyOffice.
Since I now make a copy of each document, I continue to work in OnlyOffice without problems, as it gives you the main tools you need in a word processor.
Greetings