Hi, do you have the same behavior in safe mode? * [https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Troubleshoot Firefox issues using Safe Mode] If it downloads in safe mode, then check if you do have obsolete modules installed and if yes, deactivate them. With Windows, you may also check if there is a malware * [https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware Troubleshoot Firefox issues caused by malware] Please tell us if it helps.