Blocked Plug in
I am using Safari on an iMac. Several different sites have had click throughs to material I wanted to see and I get a black screen that says blocked plug in. I have turned ON every plugin I have for these sites. Still not working.
How do I find the problem? I have tried clicking on the error and it goes nowhere.
iMac (21.5-inch Mid 2011), OS X El Capitan (10.11.6)