I've also read some forums for the fixes that I just need to repair the database, but when I check the Database in the System Configuration, the list of databases is emtpy.

Then I've manually updated the tables created by Hostinger to the contents of my local site.

@Regz84 So either you have forgotten to update something, or Hostinger have not created all data right (which happens with the custom Joomla installers provided by some providers, that's why we recommend to install Joomla always yourself, using the regular installation procedure and not any custom installer from providers or template providers).

The empty list in the database checker shows that the #__schemas is either empty, or it has a wrong extension_id in it's data.

An explanation on this and how it can be fixed can be found here: https://docs.joomla.org/J4.x:Fix_%22Database_Table_Structure_NOT_Up_to_Date%22_before_Update/en .

Of course it needs to replace the schema name in the example by the right one (which can be found out as described there and for a current 5.2.0 would be '5.2.0-2024-09-24').

But maybe that's not the only issue when something was done wrong either by Hostinger or by you with the data transfer.

For example you wrote that the issue happened when you got a notification about the available update to 5.2.0.

But your screenshot shows at the top that the site is already on 5.2.0.

So on which version did you prepare your site, and which version was the installation from Hostinger where you moved the data to? How was that done in detail?

If more things went wrong, it would not make much sense to try to repair the site, and it would be better to start again with a new installation on the target host which is the same version as the one where you have prepared your data.

You have messed up when you did this

Then I've manually updated the tables created by Hostinger to the contents of my local site.

I've followed this fix you mentioned (https://docs.joomla.org/J4.x:Fix_%22Database_Table_Structure_NOT_Up_to_Date%22_before_Update/en), and now the database is listed.

I was able to update to 5.2.0 by downloading the update (.zip) and just overwritten the files, that's why it shows 5.2.0 as its version.

I was hoping that it would fix things, but the same error messages appear when I click the Joomla update link.

So you have updated files, but the database has not been updated as there was no Joomla update run. This can not work.

Closing as not a core issue. Ask in the support forum for help.