How to fix Microsoft Word Cannot Save Document In Windows 10.
1. Try starting Word in Safe Mode
2. Turn off the antivirus software
3. Remove the Word Data registry key
4. Recreate the Word document
In case the above steps fails to fix the problem then this might be caused by certain formulas included in the document. To fix this just copy all of the text in the document in notepad. Restart word then copy the text from the notepad to the new word document. Try saving the file.