Hello

https://docs.joomla.org/J3.x:Language_Overrides_in_Joomla Can you kindly check this link if your issue if solved & it has been followed properly or not. Please do let me know if you face more trouble.

I don't want to override, I want to add a third language besides English and Arabic. On a default Joomla installation the install language function works fine. With soccer_quickstart_j3_v2.1 I get this error. "Warning The update table is not up to date. Please rebuild your update server table." The list of update servers is that of the installation, I have not made any changes

Hello, in order to add a third language, you can check out this link, it has necessary steps in order to create a multilingual joomla site. Could you kindly check and confirm if you have followed and implemented all these steps correctly or not? Please do let me know if you face trouble.

https://www.joomshaper.com/blog/step-by-step-tutorial-for-creating-a-multilingual-joomla-site

See video http://gaspare.net/sp-soccer-italiano.mp4

Thank you for sharing the video, it was very helpful. Can you kindly follow the three steps mentioned here regarding the error "The update table is not up to date. Please rebuild your update server table. No matching results.”

https://zemez.io/joomla/support/knowledge-base/troubleshooter-deal-missing-languages-issue-joomla-3-7/

Please let me know if the solution works or not.

I have updated the table, now everything is ok

Great to hear that, please do let me know if you have any more questions.

Thank you.