Sorry I do not use a Mac but will still try to help.

First of all find and backup your Firefox profile. That is easiest to find from a running Firefox, but it still should be possible to locate and back it up. (You could have more than one profile). This is important because it contains things such as your bookmarks and passwords. Firefox tries to preserve this on reinstalling but better to be safe than sorry.

• http://kb.mozillazine.org/Profile_folder_-_Firefox#Mac
  • Profile folders are in one of these locations:
    ~/Library/Mozilla/Firefox/Profiles/<profile folder>
    ~/Library/Application Support/Firefox/Profiles/<profile folder>
    The tilde character (~) refers to the current user's Home folder, so ~/Library is the /Macintosh HD/Users/<username>/Library folder.
• Back up and restore information in Firefox profiles
• Background info Profiles - Where Firefox stores your bookmarks, passwords and other user data

You may then wish to copy these instructions, and the information from the links, and then proceed with a clean reinstall. Note that involves deleting Program files but not the profile. And ensuring you have the required installer

1. http://www.mozilla.org/en-US/firefox/all/
2. Troubleshoot and diagnose Firefox problems_5-reinstall-firefox
   • How to download and install Firefox on Mac

Thanks John99. Appreciate your help. Unfortunately, this hasn't proved useful in my instance.

I have no folders called Mozilla or Firefox any more under ~/Library or ~/Library/Application Support. Fortunately, I use Sync, so should be able to get my profile back once I installed FF afresh.

Also, there is no Firefox icon in my Applications folder to drag to trash. Oddly, there was an icon (a generic thing with a ruler) labelled Firefox, so I dragged that to trash. However, this has made no difference. I'm still getting the same error on attempting a fresh install of FF23.

You will have a firefox profile. I would expect the mozillazine article to be accurate. It appears in Mac like in Windows & Linux these are hidden folders. Something I should have thought about before the last post

• http://kb.mozillazine.org/Show_hidden_files_and_folders#Mac_OS_X

Thanks! Found and backup up the profiles in ~/Library/Application Support.

Now I just need to work out what these items are that need unlocking?!

You could try this method to clear any pending update, it can not do any harm other than requiring another download.

• old archived article Updates reported when running newest version

The message is apparently from your Mac's OS. You may find more useful advice therefore on some Mac forum. I did see similar error message to yours reported in

• http://stackoverflow.com/questions/13361588/i-get-an-error-when-i-upgrade-from-xcode-4-3-2-to-4-5-2
• How to delete a file that claims it's "locked," but isn't? http://forums.macrumors.com/showthread.php?t=1220161

Thanks John99, really appreciate your help.

Re. "Updates reported when running newest version" – this isn't my problem. I had FF22 and it told me an update was available, which it is, and where to download it (rather than automatically updating as normal).

As for the links to delete a file that claims it's locked, that would all be very well if I knew which particular items it was referring to! :-)

Hello, any luck if you try the next : File >Get Info > Sharing & Permissions > clicked the + and add (Me) from the popuplist and select Read & Write.

thank you

Thanks ideato. Per my last comment here, I'm not sure which item / file the error message refers to, or yours for that matter. I've assumed you mean the .dmg file / the new FF download. I checked, and my username has Read & Write permissions already.

Then I thought, what the hell. It's been 6 hours or so since I last tried. I clicked the .dmg, dragged the FF icon onto the Applications folder, and hey presto, worked a treat! I now have FF23 installed, and with my original profile.

I'm not a computer scientist but I'm fairly techie with two decades of PC / Mac use. Yet I have no clue what just happened here. #allswellandallthat

I'll sign off with a thanks to John99 and ideato, and a sigh that we'll never know.

The article Updates reported when running newest version

Explains how to delete pending updates, I wondered if that may be part of your problem.

If necessary you can try downloading and installing a copy of Firefox from

• http://www.mozilla.org/en-US/firefox/all/

Note there should be no need to uninstall Firefox first. You should certainly not use any option to delete personal information or delete your Profile.