I want to recover my documents or know why they’d not open in a soon time.
I don’t know exactly how to reproduce that, maybe install a new version hence that showed up. Both .odt and .docx files are affected.
OS version: Manjaro Linux
App version: 9.0.0.172 (deb)
Downloaded from: official repo (extra)
Additional information: documents were created in ~ONLYOFFICE/8.3.0.97 after December of this year.
Libreoffice Writer tells me: 
Hello @Temak
Please elaborate on what happens to the document, when attempting to open it from Desktop Editors.
It opens my document, pop ups the window with following:
The document’s text despite the dialog window is visible. I can only be OK with that dialog window. But can’t edit.
Please try running the app in debug mode according to this article:
Once started in debug mode, please open a document and press F12 right away to open devtools. Please provide a screenshot with any errors you find in Console tab.