This is responding to @JTC above. He said:
Confirming that there is an issue with some .doc files after the update to 2305. Some .doc files freeze and crash Word when trying to save, or even selecting all and copying the document.
Microsoft are aware but have said they're not going to fix this one.
I do not know who JTC is to confirm this or to state that Microsoft has said they are not going to fix it. I replied to the post asking about that and have received no response. I do not work for Microsoft and never have worked for Microsoft. I am a Word user with more than 30 years of experience on primarily Windows.
I have been using both releases under 2305 in Microsoft 365 and Office 2021 and have not experienced the issue. I have tested with files in .doc and .docx format from previous versions, including new documents generated by those versions.
I have heard of one instance where this version, on a Mac, is not able to open files in .doc format that were produced by third-party software, not by Word.
Again, it is standard advice to avoid opening Word documents that are attached to email directly from the email. That is not to prevent crashes, but to prevent loss of work done on a file so opened.
I do not know that JTC is mistaken but would like to know of the source of the information. Again, it runs counter to my experience and to what I have seen on this forum and other Word forums.