Today on this site each time a page reloads or refreshes, the page hangs for several seconds and then I'm greeted with this prompt in Firefox:
If I press STOP then it works fine until I click on something (anything) which loads a new page. Has anything changed with the site's software? Again this has only been happening since today. Seems to work OK in Chrome.
EDIT: Also seems to hang in Safari but that's not actually a real web browser.
I experienced some trouble, too. Not a pop-up like yours but instead something opening below the usuals website. It said "Joomla debug console" or so. Does not show up anymore and I unfortunately did not take a screenshot.
Well since the issue has been corrected everything is off-topic now.
Safari doesn't seem to have the latest technology. For example even the newest Safari can't even use WebM VP8 whereas Chrome and Firefox already have VP9 for standard. That means the quality of the videos you watch on sites like Youtube will be lower because you are getting an older codec.