Failed to back up: The specified object was not found. (0x80042308)

I've been unable to backup my hard drive and I've been trying trying recommendations off of Google for quite a while, to no avail. When I try to backup files, I get the following error message:

The backup did not complete successfully. A shadow copy could not be created for the following reason: The specified object was not found. (0x80042308)

I tried to do this solution but in the second step there, when I right click on "Shared Folders" there is no "All Tasks" to choose: