A few minutes ago, I submitted bug report nr. 882535. Here, I provide you with a brief summary.
Often, LibreOffice Writer crashes in the middle of an intense working session, after which the system restarts.I cannot exactly reconstruct why and in which circumstances this problem occurs. However, I do have a fairly effective "workaround", which I explain below.
In about 9 out of 10 cases, I manage to recover a "read-only" document, after which I save it under another name: with a view to continuing the working session. I manage to do so in many cases, under the condition that I have taken two preventive measures before the crash:
* saving the document constantly, via control-s;
* making a backup copy of the document each five minutes.
However, in let's say the 10th case, I do not manage to recover the document anyway. In such a case, I fall back to the latest backup to continue the working session.