Windows 10 comprises several error codes, and one of the most prevalent ones is the 0x80070091 error. If your PC is showing the same, then this article can be of great help to you. So, here are the steps to fix this error.
Rename WindowsApps Folder by Booting PC on Safe Mode
https://hotmedia.site/blogs/77441/How-to-Fix-0x80070091-System-Restore-Error-on-Windows-10