You need to rename the extension to the GUID or email address as shown in the ... in the file install.rdf in the xpi file or what you see if you install the extension in Firefox.

DOM Inspector: inspector@mozilla.org.xpi

That didn't work. All the pre-existing extensions, which included those named, those by email addy, those by GUID, all were not recognized. Manual install, whether by dropping the xpi in the directory, unzipping into their own directories by name, email addy or GUID failed. Clean install whether by dropping xpi's in the directory or by unzipping, etc., also failed.

Only a few local extensions were recognized, and even this was inconsistent from user to user: Certain extensions were recognized while others were not for some users, and vice-versa for others.

What is the advantage to making it so much more difficult and tedious to install extensions globally?

Renaming xpi's to email addy fails as well.

Did you try to install such an extension to see how Firefox installs it itself?

If you copy such a folder to the extensions directory in the Firefox program directory then it should work.

You can also try locations like this or do a search for extensions that are installed globally by the distribution if there are any.

/usr/lib/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/

Both Firefox 6 and 7 failed to find any extensions and failed to find any updates using the add-on manager. Firefox 6 and 7 did not install any new extensions after they were downloaded using the browser. The downloaded extensions were put in the user's extension directory as xpi's and were never installed even after several restarts.

I took the time to manually download latest versions of all the existing extensions and placed them in the system extensions directory. Most were already current. I added a new extension as well. No updates or installations occurred when Firefox 6 & 7 started.

Does the standard Firefox 6 & 7 build actually look for /usr/lib/Mozilla or variants on the system? 3.6 apparently does not. /usr/lib/Mozilla exists here. lsof shows nothing from there linked to a running instance of Firefox of any version. It must therefore be irrelevant.

FF7 fails to install a new extension.

Clean install of Firefox 7 with a new, virgin user set up specifically to test FF7:

1. Start up FF7 as virgin user.

2. No problems reported. (New/Welcome page suppressed to save time.)

3. Go to add-on manager.

4. Search of Cookie Swap.

5. Returns *one* "Cookie Swap (Modified by ...)" This is not the expected one.

6. Close add-on manager

7. Search for Cookie Swap using browser. Find it.

8. Download extension

9. FF says it is downloading extension.

10 FF says it will install extension on restart.

11. Restart

12. On restart, Cookie Swap is not seen on lower bar. It should be there!

13. Go to add-on manager. Cookie Swap is not listed.

14. ls ~/.mozilla/firefox/$PROFILE/extensions: See "cookieSwap@cookieSwap.mozdev.org.xpi" in the directory.

15. Restart FF. maybe it forgot to install extensions?

16. FF restarts. Cookie Swap is still not there.

So. What did I miss here?

I have a somewhat similar issue in that any XPI I drop into the extensions folder under Program Files\Mozilla Firefox\Extensions just shows up as "Disabled" in the addons screen due to being "incompatible with FF 7.0.1". However, if the same extension is installed by a user into their profile then it works fine.

The same issue occurs when unzipping the contents of the XPI into a folder of the same name (there is no email address named in the RDF file)