Today i had formatted my system and installed everything again due to some problems i had before. IÂ installed firefox and imported my backup of bookmarks and settings of Firefox i had made before using Mozbackup.
But when i tried to install addons like adblockplus and few more, i started to get error, “Unexpected installation error Review the Error Console log for more details. -203 “
The error was constant with every addon and I wasnt able to install any of 
them. Finally i did a bit of googling and found the solution. IT seems that one or more out of extensions.cache, extensions.ini and extensions.rdf files associated with the Firefox extensions become corrupted and hence are causing the problems with installing add-ons.
So for solving the problem, i needed to delete extensions.cache, extensions.ini and extensions.rdf . Deleting them causes Firefox to rebuild the list of installed extensions and can solve other extension problems.
So how to find these files. Try the following steps to locate these files.
1. Click the Windows Start button, and select Run.
2. Type in %APPDATA% \Mozilla\Firefox\Profiles\ then click OK.
3. Windows Explorer opens a folder containing your profiles.
4. Double-click the profile folder you wish to open (e.g. the xxxxxxxx.default folder). You will find the required files in that folder.
5. Delete extensions.cache, extensions.ini and extensions.rdf files.
That’s all. After deleting the files, open Firefox Again and try installing the Addons. You wont be getting the problem now.
Image Credits : http://support.mozilla.com/
August 11, 2009 @ 8:09 AM
Thanks for sharing, certainly a very useful piece of information.
August 11, 2009 @ 8:36 AM
welcome mate. Thank you for standing by and taking a look around here.
August 11, 2009 @ 9:08 AM
avinashtech, there is an on going promotion for Online Armor Premium firewall, worth $39.95 here :
http://www.techsupportalert.com/get-online-armor-firewall-free.htm
I suggest to make some post about it.
P.S. You can delete this post if you want.
Cheers
August 11, 2009 @ 11:29 AM
Thanx mate for the info. i already went through it but that promo had got some issues. It seems its not valid for everywhere around the world. Until i can figure it out i wont be making a post about it.
The promo code is invalid for many places. If i can figure out the exact stuff i will make a post about it. Thank you once again for the info.
By the way, you can call me as Avinash instead of avinashtech. 🙂
Update:- I figured out the problem. And now the post is live. Check out here
http://www.avinashtech.com/internet/download-online-armor-premium-firewall-genuine-license-for-free/
By the way, you can use forums at http://www.avinashtech.com/forum/ for sharing info like this. Thank you.