Does the location where you are saving still exists? i.e. check the file path has not bee renamed or amended.
Does the drive you are saving to have sufficient space?
Can you 'Save As' to another location?
If not then check you don't have any non-standard characters in the file name.
One of the forum moderators. Versions 6.5 to 25 Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10 Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10