I know this was 3 years ago but, I just started having the same issue. Found a temporary fix that you can try everytime this pops up. To be more specific I got this issue while trying to dowload and install mods. My fix is to find where Vortex stores your mods that are downloaded from Nexus. Mine looks like this: (Not sure if this is the default location or if I set it.) C:\Users\[your user]\AppData\Roaming Find this in your File Explorer. In Roaming there is the Vortex Folder. Right click on it and then click on Properties and then on the pop-up box deselect Read Only. Then Apply and Okay. Somtimes it won't let you apply because Vortex is trying to use a file in there. So close Vortex if need be. Hope this helps. Will update if I can find out what change in the first place to cause this issue.
