Did it work in Firefox 21 before this week's Flash update? If you haven't updated, you can check for updates using [https://www.mozilla.org/en-US/plugincheck/]. If it hasn't worked at all in Firefox 21, were you able to use the site successfully in earlier versions of Firefox, or is this the first version you've tried with the site? ---- When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site. (1) Bypass Firefox's Cache Use Ctrl+Shift+r to reload the page fresh from the server. Alternately, you also can clear Firefox's cache completely using: orange Firefox button (or Tools menu) > Options > Advanced On the Network mini-tab > Cached Web Content : "Clear Now" If you have a large hard drive, this might take a few minutes. (2) Remove the site's cookies (save any pending work first). While viewing a page on the site: * click the padlock/globe icon in the address bar > More Information > "View Cookies" * right-click and choose View Page Info > Security > "View Cookies" * Alt+t (open the classic Tools menu) > Page Info > Security > "View Cookies" In the dialog that opens, you can remove the site's cookies individually. Then try reloading the page. Does that help? ---- Possibly related thread: * On Windows 8, no browsers will upload files larger than 2MB (fail/retry over and over again): [https://support.mozilla.org/en-US/questions/957335 How do I get wetransfer.com to work again?]