Today I tried to install some new browser extensions into the latest Firefox 0.9.3 browser and couldn’t figure out why nothing was happening. I first tried opening the XPI file directly from the Mozilla Update extensions page. I clicked on one of the extensions I wanted (Adblock, highly recommended), and clicked the “Install Now” link. Nothing happened, like it wasn’t recognizing my click.

Next attempt: Download the XPI file, and try to install it that way. I saved the adblock-0.5-dev.xpi file to my disk, then went into Firefox’s File / Open File… menu to open it. Nothing happened. It was like Firefox was just going to ignore the fact that I asked it to open the file.

Next attempt: Drag the XPI file from the folder into Firefox and have it open the file that way. Still, nothing happened.

I went to the Tools / Extensions menu item to see if something was stopping me from installing extensions, an error message, something. No joy.

I searched around the Internet looking for people with similar problems. I checked out the Firefox help on I read the FAQ. I searched through the Firefox forum. Nothing pointed me in the right direction.

Finally, I tried hunting around in all my Tools / Options… settings to see if something there would help me out. Hmm. Tools / Options / Advanced / Software Updates / Allow web sites to install software. There it was. I had, many months ago, unchecked this box for security reasons when I first installed my browser. Even though I was installing the XPI file locally and not from a web site, that security option was stopping the extension from being installed (which is a good thing).

Summary: User error. Firefox was doing exactly what I had told it to do. While I’m suitably chagrined, it sure would have been nice if Firefox would have told me what I was doing wrong rather than ignore my attempts to install the XPI files. How about an error dialog, “Your security settings prohibit installation of browser extensions.”

Next stop: A check of the bugzilla site to see if this feature is on the to-do list.

Update: Bugzilla has this problem logged as Bug 248486.

Two duplicate bug reports were filed by others similarly frustrated. It looks like someone wrote a patch for it, so maybe the fix is in the nightly builds even now. But I’ll wait until Firefox 1.0 comes out to enjoy the fix.