Popup that says "Error", cache not cleared

[GRMule]

Plugin stopped working in v31, problem persists in v32.0.1

Windows 7. Firebug, Web Developer toolbar, Colorzilla addons also installed

Screenshot of error popup:

[PandyLegend]

I am also getting this error in Firefox 35
Windows 7. Firebug. Web Developer toolbar.

[nw360git]

I have the same problem, it doesn't clear the cache in Firefox 52.0 for mac osx

[GRMule]

I personally solved this problem by switching to Chrome. The "Clear Cache" extension there is an excellent way to provide this functionality in Chrome, just as Chrome is an excellent replacement for the dying and increasingly irrelevant Firefox. Good luck to all.