Does the error always have that pattern of a cloudfront''.''net address and a .js (JavaScript) type file? It would be odd if all sites used the same script. It could perhaps be something added by one of your extensions. If you have extensions you could live without for a few hours, try disabling those on the Add-ons page. Here's how to get there: Either: * click the Extensions button (puzzle piece) on the toolbar > Manage Extensions * Ctrl+Shift+a (Mac: Command+Shift+a) * "3-bar" menu button (or Tools menu) > Add-ons * type or paste '''about:addons''' in the address bar and press Enter/Return In the left column of the Add-ons page, click Extensions. On the right side, find the "Manage Your Extensions" heading. ''If there is at least one extension before the next heading -- "Recommended Extensions" -- please continue:'' Then cast a critical eye over the list below that heading. Any extensions Firefox installs for built-in features are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything suspicious or that you just do not remember installing or why? If in doubt, disable (or remove). For your privacy and security, don't let mystery programs linger here. Otherwise, you can temporarily disable individual extensions by clicking the blue slider switch. Any difference as you browse? ''Note: Sometimes extensions can frustrate access to this page. In that case, first restart Firefox in its Troubleshot Mode and then try again.'' See: [[Diagnose Firefox issues using Troubleshoot Mode]] -- Open, not Refresh.