Updated joomla to 4.3 following steps as advised. All seemed to work fine, no issues found. Updated just community builder without issue.
Couple days later renewed my subscription to update the plugins, had not noticed it had lapsed, and several of the plug ins failed. I then went to install the plugins one at a time to see if that helped and could not access the system page. The admin menu opened but only get the JError message in the body. Logged me out after a bit of time. Went to log in at a later date and no option to do so nor anything other than screenshot attached.


An error has occurred.

0 Class "JError" not found

Call stack
# Function Location
1 () JROOT/plugins/system/cbredirectbot/cbredirectbot.php:44
2 plgSystemcbredirectbot->__construct() JROOT/libraries/src/Extension/ExtensionManagerTrait.php:242
3 Joomla\CMS\Application\CMSApplication->loadPluginFromFilesystem() JROOT/libraries/src/Extension/ExtensionManagerTrait.php:160
4 Joomla\CMS\Application\CMSApplication->loadExtension() JROOT/libraries/src/Extension/ExtensionManagerTrait.php:94
5 Joomla\CMS\Application\CMSApplication->bootPlugin() JROOT/libraries/src/Plugin/PluginHelper.php:235
6 Joomla\CMS\Plugin\PluginHelper::import() JROOT/libraries/src/Plugin/PluginHelper.php:193
7 Joomla\CMS\Plugin\PluginHelper::importPlugin() JROOT/libraries/src/Application/CMSApplication.php:739
8 Joomla\CMS\Application\CMSApplication->initialiseApp() JROOT/libraries/src/Application/AdministratorApplication.php:354
9 Joomla\CMS\Application\AdministratorApplication->initialiseApp() JROOT/libraries/src/Application/AdministratorApplication.php:165
10 Joomla\CMS\Application\AdministratorApplication->doExecute() JROOT/libraries/src/Application/CMSApplication.php:278
11 Joomla\CMS\Application\CMSApplication->execute() JROOT/administrator/includes/app.php:63
12 require_once() JROOT/administrator/index.php:32


Am going through logs but thought I should get the support train moving. Any suggestions welcome.

Removal of folder corrected jerror.
It also required I turn of and back on the TFA before I could log in.
It now is logging me out very quickly. Session is set to 120 minutes and yet after less than a minute of inactivity it throws back to the log in again.

I have confirmed it only happens with TFA. Off and session time out is as expected. On and it times out after around 30 seconds. Any advise would be welcome.

update: Nope, not TFA related. jsut a little more various timing but looks to be less than a minute or so max.

Likely the actual issue is this, github.com/joomla/joomla-cms/issues/35244 So may be separate issue.
And this seems to have solved it.
github.com/joomla-framework/session/pull/55/files#diff-632ffa4c0341fee13a5f567a65a2310fc1e544ff5a8f95a3a781d12a23979455