Hi, This may happen if the PDF is opened inside the browser by the PDF plugin. In '''Tools''' ( or '''Alt''' + '''T''') > '''Options''' > '''Applications''' look for or type PDF in the search box and for the '''Action''' on the right change it to '''Save File''' or click '''Use other...''' and browse to the PDF main exe and select. Please see [https://support.mozilla.com/en-US/kb/Options%20window%20-%20Applications%20panel this] and [https://support.mozilla.com/en-US/kb/Managing%20file%20types this.] ............................................................................................................................... Useful links: [https://support.mozilla.com/en-US/kb/Options%20window All about Tools > Options] [http://kb.mozillazine.org/About:config Going beyond Tools > Options - about:config] [http://kb.mozillazine.org/About:config_entries about:config Entries] [https://addons.mozilla.org/en-US/firefox/addon/whats-that-preference/ What's That Preference? add-on] - Quickly decode about:config entries - After installation, go inside about:config, right-click any preference, enable (tick) MozillaZine Results to Panel and again right-click a pref and choose MozillaZine Reference to begin with. [https://support.mozilla.com/en-US/kb/Keyboard%20shortcuts Keyboard Shortcuts] [https://support.mozilla.com/en-US/kb/Safe%20Mode Safe Mode] [http://kb.mozillazine.org/Problematic_extensions Problematic Extensions/Add-ons] [https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes Troubleshooting Extensions and Themes]