It looks that the Stubhub website has a problem with "en-US" in the accept header and with some language combinations gives the "You don't have permission to access..." error. What works is adding a second "en-XX" language or other not English language or if you have "en" as second then add a third language (don't have to be "en-XX" as something like "fr" works). *https://support.mozilla.org/en-US/kb/choose-display-languages-multilingual-web-pages See also this thread: *[/questions/1384569] One website not loadable with Firefox only (Chrome works fine)