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First of all, please keep in mind that only latest major release which 3.1 is supported, secondly since this issue looks like caused by javascript conflict and it's not happening on fresh install of Joomla and JomSocial, then I suggest to set your site under maintenance mode, and try to disable all extensions exept of those listed below also try to switch to default Joomla/JomSocial template, in such way you should be able to track this problematic extension. You can also try to download whole page on your hdd and create an copy of it on some dev domain, and there disable all extensions.
Authentication - Joomla!
User - Joomla!
Azrul System Mambot For Joomla
jomsocial facebook connect
I updated to 3.1 and unfortunately that didn't fix it. Will I lose any configuration/customizations I have made if I disable the extension? I'm thinking it will and that is not a good idea with the number of extensions I had to configure just to get this site to do what I need it to do. What does the maintenance mode do? Can you make any suggestions on how to fix the JS error?
This's not an JS error, like I said it's caused by some other extension. You can check that everything is working quite well on our community page for instance. This's why I suggest to disable all extensions, in such way you should be able to track this problematic extension.