Do you have a stack trace? What PHP Version you are running? That is an 3.10.11 that raises this error right? There was a similiar issue that @coolcat-creations had but that was on 3.10.11 and updated from there.

Did the issue come up with the updated package too?

The issue shows on 3.10.12 with PHP Version 8.2.5

Does the same issue come up with PHP 8.1 or 8.0? There are a few known issues with PHP 8.2

Same issue when using PHP 8.0 and PHP 8.1

Thats nothing to do with my issue, my issue happened before the update I disabled all 3rd party but the issue is still there.

Can you look into the PHP error log whether there is an error when looking for an update before? When you can also try is to reset the updater table via: Extensions -> Manage -> Updates -> Clear Cache.

Not sure about before when updating to 3.10.12, but currently (after the update) when re-attemtping to install Core files the following entries are made into the PHP Error Log

2023-07-13 11:26:25.069720 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP Warning: Attempt to read property "downloadurl" on null in /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/administrator/components/com_joomlaupdate/models/default.php on line 301\n
2023-07-13 11:26:25.069752 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP Stack trace:\n
2023-07-13 11:26:25.069758 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 1. {main}() /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/administrator/index.php:0\n
2023-07-13 11:26:25.069763 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 2. Joomla\CMS\Application\CMSApplication->execute() /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/administrator/index.php:51\n
2023-07-13 11:26:25.069767 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 3. Joomla\CMS\Application\AdministratorApplication->doExecute() /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/libraries/src/Application/CMSApplication.php:225\n
2023-07-13 11:26:25.069774 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 4. Joomla\CMS\Application\AdministratorApplication->dispatch($component = uninitialized) /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/libraries/src/Application/AdministratorApplication.php:159\n
2023-07-13 11:26:25.069780 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 5. Joomla\CMS\Component\ComponentHelper::renderComponent($option = 'com_joomlaupdate', $params = uninitialized) /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/libraries/src/Application/AdministratorApplication.php:101\n
2023-07-13 11:26:25.069787 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 6. Joomla\CMS\Component\ComponentHelper::executeComponent($path = '/home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/administrator/components/com_joomlaupdate/joomlaupdate.php') /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/libraries/src/Component/ComponentHelper.php:377\n
2023-07-13 11:26:25.069805 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 7. require_once() /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/libraries/src/Component/ComponentHelper.php:402\n
2023-07-13 11:26:25.069809 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 8. Joomla\CMS\MVC\Controller\BaseController->execute($task = 'download') /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/administrator/components/com_joomlaupdate/joomlaupdate.php:18\n
2023-07-13 11:26:25.069817 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 9. JoomlaupdateControllerUpdate->download() /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/libraries/src/MVC/Controller/BaseController.php:702\n
2023-07-13 11:26:25.069821 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 10. JoomlaupdateModelDefault->download() /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/administrator/components/com_joomlaupdate/controllers/update.php:48\n

2023-07-13 11:26:25.069828 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP Warning: Attempt to read property "_data" on null in /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/administrator/components/com_joomlaupdate/models/default.php on line 301\n
2023-07-13 11:26:25.069836 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP Stack trace:\n
2023-07-13 11:26:25.069850 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 1. {main}() /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/administrator/index.php:0\n
2023-07-13 11:26:25.069854 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 2. Joomla\CMS\Application\CMSApplication->execute() /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/administrator/index.php:51\n
2023-07-13 11:26:25.069865 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 3. Joomla\CMS\Application\AdministratorApplication->doExecute() /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/libraries/src/Application/CMSApplication.php:225\n
2023-07-13 11:26:25.069891 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 4. Joomla\CMS\Application\AdministratorApplication->dispatch($component = uninitialized) /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/libraries/src/Application/AdministratorApplication.php:159\n
2023-07-13 11:26:25.069908 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 5. Joomla\CMS\Component\ComponentHelper::renderComponent($option = 'com_joomlaupdate', $params = uninitialized) /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/libraries/src/Application/AdministratorApplication.php:101\n
2023-07-13 11:26:25.069918 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 6. Joomla\CMS\Component\ComponentHelper::executeComponent($path = '/home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/administrator/components/com_joomlaupdate/joomlaupdate.php') /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/libraries/src/Component/ComponentHelper.php:377\n
2023-07-13 11:26:25.069922 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 7. require_once() /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/libraries/src/Component/ComponentHelper.php:402\n
2023-07-13 11:26:25.069930 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 8. Joomla\CMS\MVC\Controller\BaseController->execute($task = 'download') /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/administrator/components/com_joomlaupdate/joomlaupdate.php:18\n
2023-07-13 11:26:25.069940 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 9. JoomlaupdateControllerUpdate->download() /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/libraries/src/MVC/Controller/BaseController.php:702\n
2023-07-13 11:26:25.069944 [NOTICE] [3623041] [T0] [127.0.0.1:47418#APVH_www.sprintswac.tk:443] [STDERR] PHP 10. JoomlaupdateModelDefault->download() /home/mycoo660/domains/sprintswac.tk/public_html/iconnect/3/administrator/components/com_joomlaupdate/controllers/update.php:48\n

Hmm that sounds like to be an issue of the update not beeing recived correctly. Does that solve itself when you are deleting the #__updates table so the update will be fetched again?

You mean delete the _updates table from the database?

Same message displays with an empty _updates table

Hmm Yes i had an empty #__updates table in mind not deleting it. Please reach out to me via [removed] so we can coordinate a meeting where we can take a look into the site and debig the issue. As I can not reproduce the issue on my end its hard to diagnose the issue while that problem does not come up to me.

I will write to you soon, but I just wanted to mention that for some reason as well, the error only occurs when Joomla Update is set to default.

Have you reached out to me already? Havn't saw a mail from you till now.

We are not fixing bugs for Joomla 3 anymore, which is why I'm closing this issue.