I faced the same issue.
I am no expert but I have one solution that worked.
1) I connected using ftp to my webspace.
2) Browsed to the plugins folder where wordpress is installed.
3) Copied a backup of the Quick Cache plugin folder to my local PC.
4) Deleted the Quick cache plugin folder from the webspace.
Now it works fine. Will reinstall quick cache plugin once this issue is resolved.
