I did I accidentally deleted this user account on your test site "matissou" but that is not this user account issue actually.

After consult with our developer regarding this, the reason why you hitting that error during update your site Joomla is because your Joomla user table has duplicate username, you can run this following SQL query to see which account has duplicate username, it shouldn't have this happen.

select username from jasm1_users

group by username having count(username) > 1;

select * from jasm1_users where username = 'sandrine';

So you have to see which user account is the real one, either you delete it or update another username to different name.

After you done it, then you have to execute this SQL query because this is Joomla latest version trying to execute index all of your existing user under #__users table.

ALTER TABLE `jasm1_users` ADD UNIQUE INDEX `idx_username` (`username`);

Thank you very much Arlex.
The problem is now fixed.

Philippe

Hi there,

You are most welcome. Glad to hear that your issue has been resolved now.

Just for your information, I have locked and marked this thread as resolved to avoid confusions in the future. Please start a new thread if you have any other issue in the future so it will be easier for us to manage your inquiries.

Thanks for understanding.