In LO 6.3.6.2 (x64) defaults to "save as"

Since upgrading I cannot save a new file. Save automatically changes to “save as” & the message “File not found. Check the file name and try again.” The happens regardless of the file extension, for both Writer & Spreadsheet files. How do I fix this?

Can you save anything at all? If not it is probably a recent change to operating system anti-ransomware settings

Mac You probably need to give LibreOffice full disk access from System Preferences > Security & Privacy. See this site on how to do it if you aren’t sure: Explained: What is Full Disk Access & Full Permissions on macOS Mojave

Windows

If it is something else you might want to explain what you can and can’t do when you try to save and give operating system details. Cheers, Al