You could check in phpMyAdmin if the update site is really missing:

SELECT * FROM `#__update_sites`;

(replacing the #__ by your actual table prefix).

There should be a record with name="Joomla! Core" and type="collection".

What you also should check: Is there an extension record for the "files_joomla" extension?

SELECT * FROM `#__extensions` WHERE `type`='file' AND `element` = 'joomla';

There should be such a record.

Finally there should be an entry in the #__update_sites_extensions table, referencing the update site and the extension mentioned before:

SELECT * FROM `#__update_sites_extensions` WHERE `update_site_id`=X and `extension_id`=Y;

with X being the update_site_id from the first query to the #__update_sites table, and Y being the extension_id from the second query to the #__extensions table.

Please check that and report back the results.

Then we can let you know how you can fix it in phpMyAdmin if something is missing.

Finally, when all that is there, it needs to change the update source in the options of the Joomla Update Component from "Default" to "Next" to find the update to 4.4.14.

Many thanks Richard.

There is no "Joomla! Core" in the _update_sites table. That means I cannot check the _update_sites_extensions table.

The Joomla Update Component is set to Next.

Looks like I need to manually create a entry in the respective tables. I am currently doing this on a localhost installation to check it works before updating the live site.

@escrime You still should check the extensions table for the mentioned record for "joomla_files". If that is missing, too, you have to add that also.

Sorry, I missed that.

Yes there is a record for "joomla_files".

@escrime Ok, then you can do the following to insert the missing records (replace the #__ by your actual table prefix including the underscode):

INSERT INTO `#__update_sites` (`name`, `type`, `location`, `enabled`, `last_check_timestamp`) VALUES
('Joomla! Core', 'collection', 'https://update.joomla.org/core/list.xml', 1, 0);

Then check again the table and note the update_site_id value of the previously inserted record.

Then insert a record into the #__update_sites_extensions table, with X being the previously noted update_site_id, and Ybeing the extension_id of the record for "joomla_files" in the #__extensions table:

INSERT INTO `#__update_sites_extensions` (`update_site_id`, `extension_id`) VALUES
(X, Y);

Then check if the update site is correctly shown in the list of update sites.

If that is the case, switch the update source to "Next" in the options of the Joomla Update Component.

After that, use the button to check for updates if none has been found yet.

The result should be an update to 4.4.14 being found.

But before you update, make sure that you make a backup so you can fall back in case of problems, and carefully check your 3rd party extensions. Check that they are up to date with the latest version which they have for Joomla 3.

@richard67 Many thanks for your invaluable help.

On the localhost installation I have successfully updated the two records in the _update_site_id and _update_sites_extensions tables and the Joomla! Core site is now listed and enabled.

However, the Joomla Update component says I am on the latest version andthere is no Pre-update tab to check extensions. I have cleared the cache and refreshed several times so I am not sure what I am missing.

@escrime As I wrote you have to change the update source from "Default" to "Next" in the options of the Joomla Update Component. Have you done that?

If yes and you still see no update, then your PHP version or the database version might not filfill the minimum requirements for Joomla 4.

Please check and report back PHP version and database type and version.

@richard67 I have updated the live site too now and it tells me I am on the latest version. Not sure if I should reinstall the core files.

@escrime Again asking: Have you changed the update source from "Default" to "Next" in the options of the Joomla Update Component?

Have you check my previous comment?

Have you checked PHP and databae versions? I've asked you to report back these versions.

It seems you don't really read what I write.

@richard67 Yes the Joomla Update Component is on "Next".

PHP is 7.4.33 and DB type and version are mysql and 8.0.43-34 respectively.
I thought the minimum php for J4 is 7.2.5 and MySQL 8.0+ (https://manual.joomla.org/docs/4.4/get-started/technical-requirements/) so the configuration should be fine.

@escrime Could you check again in database for the updatesites table and report back the result, i.e. the details of the record for the core?

Joomla! Core collection https://update.joomla.org/core/list.xml 1

@escrime After switching to "Next" in the update component's options, the URL should have changed from https://update.joomla.org/core/list.xml to https://update.joomla.org/core/sts/list_sts.xml . Obviously that has not happened for you (or you haven't really changed the option). So maybe it is really better if you first reinstall the core files and then check and change again from "Default" to "Next".

The channel was set to Next a while ago. I tried setting it back to Default, saving it and then reverting to Next.

I will try reinstalling the core files and let you know :)

If that does also not help, change the update source to "Custom URL" and use this URL:
https://update.joomla.org/core/sts/list_sts.xml

P.S.: And your version is really 3.10.12? Not a nightly build with e.g. 3.10.13-dev?

Just updated the core files and the list has not changed. Should I try setting the update channel to something else, saving, then reverting to Next? I have tried the Default setting again, saved and reverted.

Read my previous comments.

Thanks. Not seen until manually refreshed which is why I missed them.

The version is 3.10.12.

The database is not being updated when selecting and saving the custom url.

The database is not being updated when selecting and saving the custom url.

Then it seems changes in the options of the update component aren't saved at all?

You could update the URL of the core update site to https://update.joomla.org/core/sts/list_sts.xml in database with phpMyAdmin.

If that also doesn't work then I have no idea (except of the very unlikely case you are looking into the wrong database for that site. Unlikely, but I've had such a case in past where someone checked the backend of a site and looked into the database of another site).

There's only one database on the wamp installation :)

I was going to suggest manually updating the entry so am pleased for your confirmation because that has worked!

Many thanks Richard. It has taken me weeks to get this far. Now I can make some progress, though there are a lot of extensions to update/remove/replace!

Much appreciated.

Then l will close this issue as resolved. No idea what happened, but it is definitely not something related to our update sites or a general problem with 3.10.12.