availability: January 2017
After upgrading from Firefox 2.x to Firefox I found myself unable to install new plugins. It would keep on telling me that it would install the plugin at the next restart of Firefox.
Error: When I opened the Error Console it would say:
[Exception... "Component returned failure code: 0x80520012 (NS_ERROR_FILE_NOT_FOUND) nsILocalFile.persistentDescriptor" nsresult: "0x80520012 (NS_ERROR_FILE_NOT_FOUND)" location: "JS frame file:///Applications/Firefox/Firefox.app/Contents/MacOS/components/nsExtensionManager.js getAbsoluteDescriptor :: line 438" data: no]Solution: