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Closed Public Technical Support / Bugs Ticket #809

Update J2C 4.1.1 > 4.1.3 -> Error Multiple FOF Libraries

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Conversation

Marc Pradel

Hi Olivier,

when I try to install the newest Version I get the error message that

Installation blocked: the following FOF library directories were found alongside the F0F library used by J2Store: fof30, fof40. Multiple FOF installations in the same Joomla instance cause class-loading conflicts. Please uninstall those libraries before installing J2Commerce. Check the libraries. If no library is present, you may have to delete the folder(s) manually.


But I do not see multiple installations of the library only FOF and F0F? (s. attachment).

 

Regards,

Marc

Attachments

Bildschirmfoto 2026-06-02 um 16.04.28.png
Olivier Buisard Staff

Hi Marc, yes, as you can see, you have 2 different versions of the library: f0f and FOF. FOF has to be removed.

Casing and use of 0 or O does not matter. It's the same library with different 'flavors'.

Olivier.

Marc Pradel

Hi Olivier,

thanks for the quick reply. After uninstalling FOF is gone, but when I try to insall 4.1.3 the error message still appears. Any Idea?

Kind Regards,

Marc

Olivier Buisard Staff

Hi Marc,

even if the libraries are not in the list of libraries in the console, some may still be on the server, so you have to look at the file structure of your server. Check under /libraries. Report any fof/fOF... directory you find and I will let you know which one(s) to delete.

Olivier.

Marc Pradel

Hi Olivier,

removed the folders 'fof30' and 'fof40' and now the installation works! :-)

Hopefully there are no other extension which use the old fof versions?!

Kind Regards,

Marc

Olivier Buisard Staff

Marc,

no, Akeeba was using those libraries before Joomla 4 and since these libraries have been outdated for quite some time, I doubt any extension is still using them since the libraries cannot function properly unless patched like we patched the one we included with J2Commerce 4.

Olivier.

Edited by Olivier Buisard on 06-03-2026 12:53 EDT
Olivier Buisard Staff

We included this install 'stopper' in the latest versions of j2Commerce v4 to make sure sites do not carry obsolete libraries that users are not aware of.

'Dead' code can compromise your site, because it is not maintained and can be prone to breaches.

Olivier.

Marc Pradel

Hi Olivier,

thanks for the explanation, sounds like this is a good approach for keeping the installation clean. :-)

 

Regards,

Marc