Firefox is showing me the same blocked (and cancelled) download on each startup. Firefox tries to download same file every time I open it. I have seen this issue in several threads. I want to share my experience in resolving it: In your Firefox profile folder (%appdata%\Mozilla\Firefox) look for the file download*.json (the asterix represents some characters I did not record). If it contains the strange link for that file he is trying to download all over again at each startup, delete the text ad save the now empty file. At the following startup, the issue should be resolved and the download*.json should disappear from your profile folder. I hope this helps. Additional info: This happened to be after trying to download a file from bit-files.com. < -- DO NOT OPEN ONLY FOR WARNING This issue was reported also for depositfiles.com by others. < -- DO NOT OPEN ONLY FOR WARNING Other threads on the same issue: Firefox tries to download same file every time I open it - https://support.mozilla.org/en-US/questions/922373 firefox 28 automatically tries downloading a file when it starts - https://support.mozilla.org/en-US/questions/992386 Firefox is showing me same blocked (and cancelled) download on each startup - https://support.mozilla.org/en-US/questions/1333402