06-06-2018 12:07 AM
If you are using Windows Defender as your AntiVirus solution, it may be due to the its Controlled Folder Access setting.
See the link below to disable that "feature" and test the file save again to see if that is the problem or not.
If you sure the application you are using to save the file is safe, you can create an exclusion for that application, and then re-enable the Controlled Folder Access safety feature.
Windows 10's "Controlled Folder Access" Anti-Ransomware Feature Is Now Live