More often than not the error is referring to a pop up which also plant cookies on your machine!
Deleting all cookies is NEVER a good idea! Takes hours to get back on track. As simple as I can make it, find your cookies folder, read through EACH AND EVERY cookies file and kill every one’s name you don’t recognize. Names are site names. Probably take an hour or so. You’ll most likely end up killing 75% of your total cookies! Don’t worry about it!
When deleting, hold down the SHIFT key and hit the DEL key. The file(s) will be permanently gone! For a consecutive list of files, click on first file, hold down shift key, go to last file, click on last file, all files will be selected/highlighted. You’re already holding shift key, hit delete, all those files will permanently go away!
If you have a Mac, disregard all above! Except part about pop ups!!
I did tech support for about 6 years, years ago!!