Just got this error while upgrading to 3.9.1:

Matomo encountered an error: Call to undefined method Piwik\Plugin\Manager::getPluginDirectory() (which lead to: Circular dependency detected while trying to resolve entry 'Piwik\Twig')

Got also on two instances this error...
After returning back all seems to work but I think the update is not complete?

After upgrade a 3.8.1 enterprise version to 3.9.0 enterprise version and another upgrade to 3.9.1 enterprise version UI show 3.9.1 but in database, core still in 3.8.1, and plugins like version_MediaAnalytics still in 3.3.1.

The archive job won't run because they are missing table :

Table 'matomo.matomo_log_media_plays' doesn't exist - in plugin MediaAnalytics

The ./console core:update didn't return anything

I've this php errors
PHP Fatal error: Class 'Piwik\Plugin' not found in [...]/htdocs/plugins/Installation/Installation.php on line 23

After adding
in Installation/Installation.php
use Piwik\Plugin;

It's ok
./console core:update work and everything seem fine (value core and plugins version up to the good file version of 3.9.1 release in database matomo_option)

Much like Sh4d0wF1gh7, it was fine after returning to the same install script. It was marked as "already updated".

Unsure if actually complete however.

We are still on 3.8.1 because of this problem. Is there an expected date when this will be fixed?

@larsen0815 This bug has already been fixed with 3.9.1, but as during the update the old code (with the bug) is running, you will still see the error when upgrading to 3.9.1. But the next upgrade from 3.9.1 should then be fine.
See here: #14227 (comment)

You can simply do a manual three step upgrade (https://matomo.org/docs/update/#the-manual-three-step-update) to avoid the problem. The error is part of the one click updater.

Ah ok. I was already using that workflow. Upgraded my dev system and got no errors that way.

Got this error using the 1 click updater from 3.8.1 to 3.12.0. I reloaded the page, was prompted to login, then prompted to run the database update. The upgrade appears to be complete, but I'm wondering if anything was missed.

Before trying the one-click updater, we ran the command line version and it reported:

./console core:update

Everything is already up to date.

Despite running this command on 3.8.1