Firefox cancels downloads before they begin

Question

About a week ago, I noticed that a download from Firefox didn't complete. I looked at the download dialog and the download had been cancelled. I clicked the download and restarted it; it seemed to start but then I couldn't open the file.

I then copied the download link into Chrome and it worked as normal. I went to the file and double clicked it but my system told me I didn't have permissions to open the file. I right clicked and went to Properties and there was a button at the bottom called "Unblock" - I unblocked the file and it then worked as normal.

For the last week or so, I have been downloading files with this technique but it's a pain. What is going on here? I clicked around in Firefox options and found no sign of a setting that needs my attention. Has anyone else seen this?

Answer 1

Mozilla's article Enable downloads blocked by Security Zone Policy might have an explanation for the problem:

Downloading an executable file (e.g., an .exe or .msi file) may fail, with the Downloads window showing Canceled under the file name.

This happens because Firefox honors your Windows security settings for downloading applications and other potentially unsafe files from the Internet.

Evidently, Chrome doesn't care about the Windows security setting, but Firefox does.

The solutions proposed are:

A. Bypass Windows Security Policy check

You can add the preference, browser.download.manager.skipWinSecurityPolicyChecks and set it to true. This will bypass the Windows Security Policy.

B. Reset system Internet Security settings

You can reset your system Internet security settings in Internet Explorer.

Or for a less-destructive version of solution B, just go into Control Panel -> Internet Properties -> Security Tab, scroll down to Miscellaneous > Access data sources across domains, then change it from "Denied" to "Prompt".

Answer 2

For Windows XP:

Start > Run > type:

regsvr32.exe urlmon.dll

Once registered, the download problem should get solved. This should also work for Windows Vista and Windows 7.

Answer 3

Did you get any errors from your Error Console (Ctrl + Shift + J) ?
Have you installed a new add-on / application recently?