I've had this error a fair bit.. it comes and goes. It's not just on mozilla.com, happened on readitlaterlist.com as well.

A work around is right click > save as on the extension link... then open the .xpi file from your local machine

Guys i think i solved this issue :D All what you have to do is go to about:config then click "I'll be careful i promise" now right click somewhere then click New>String and name it: xpinstall.enabled and set the value to true

All the downloads should work now

Thank you. It worked. I could not download for some reason, I followed your directions and now I can. One thing, though, first I had to restart. Don't know if restart of Firefox only was necessary or of computer and firefox. After I went into config, I did what was necessary and it didn't work. I closed down everything and when I came back, it worked. Dayton

Did this still can't download any plugins. I even tried to use IE and I got to the plugin that I wanted. Mozilla system knew that I was not using Firefox at their site and asked me to DL Mozilla or download the plugin anyway. I told them I wanted to DL anyway. IE then said it could not display the page and that the server could not be found. WONDERFUL! Does addons.mozilla.org even exit? You can't even get live chat to work at Mozilla it always says that they are closed.

I also tried that to download plugins, but when I right click the link it does not show me the download option as you mention.

what about on Windows 7 SP1 ^4 bit OS

I have firefox 10.0.02 .. So this little xpinstall thing is non-existent in my version. I tried adding it into the about:config and STILL there is nothing that will help. This is really beginning to be frustrating since I need these addons.. Can someone please give me an UPDATED SOLUTION that can solve my problem with the recent version of firefox? I cleared the cache, reinstalled, and still nothing. Thinking about switching to chrome... Please help.

Thank you for your help! This finally fixed my problem!

"Guys i think i solved this issue :D All what you have to do is go to about:config then click "I'll be careful i promise" now right click somewhere then click New>String and name it: xpinstall.enabled and set the value to true"

Brilliant! That worked for me. I can confirm you need a complete system reboot first though. Many thanks!

I had the same issue today. I opened up LiveHttpHeaders and started looking. I found the last redirect wasn't resolving so I found the mirror site associated with the release.mozilla.org. I was able to access that directly to get the add-on I needed. I guess something is wrong with the name resolution for release.mozilla.org

Here are the two add-ons I found and able to download direct from the mirror. http://www.mirrorservice.org/sites/releases.mozilla.org/pub/mozilla.org/addons/1843/firebug-1.9.1-fx.xpi http://www.mirrorservice.org/sites/releases.mozilla.org/pub/mozilla.org/addons/78928/

the addon are on the site "releases.mozilla.org". and it looks like this site is off. try to ping the site, if you could then you have other problem.

I tried all of the solutions posted in this thread but none of them worked :( Please help!