The compat6 plugin exists already in 5.4-dev, but there it is only an empty stub without a constructor, so this PR here does it at the right place (6.0-dev).

I don't have time for a real test now, but by review the PR is right, I think.

@laoneo - where am I supposed to find:

oomla\Plugin\Behaviour\Compat6\Extension\Compat6::__construct(): Argument #1 ($dispatcher) must be of type Joomla\Event\DispatcherInterface, array given

I'm not seeing that anywhere - in the Joomla Backend, or in any log...
(I have tried Maximum Error Reporting: on with or without Debug on, with or without Log Almost Everything and/or Log Deprecated API and can't get it to show....)

I should have specified (fresh installation, Joomla 6 Nightly from Thursday, 28 August 2025 00:55:42 UTC and Install Blog Data, French added, and Install Multilingual Sample Data).

thanks :)

OK, @laoneo so this might or might not be related or help... . Since I couldn't find this error:

0 Joomla\Plugin\Behaviour\Compat6\Extension\Compat6::__construct(): Argument #1 ($dispatcher) must be of type Joomla\Event\DispatcherInterface, array given, called in /home/lights/public_html/_j6b2n/plugins/behaviour/compat6/services/provider.php on line 34

I went on to test PR #46002 #46002, (Downloaded the Update Package and installed it) after which I DID receive the above error message with a stacktrace ;(

`

(disabling plg_behaviour_compat6 via phpMyAdmin (after clearing cache) let me 'restore' the site).

Then I installed again J6! Nightly, turned on Compat. Plugin 6 and applied the Patch for PR #45998 and it crashed (no error before the PR applied):

An error has occurred.
0 Joomla\Plugin\Behaviour\Compat6\Extension\Compat6::__construct(): Argument #1 ($config) must be of type array, Joomla\Event\Dispatcher given, called in /home/lights/public_html/_j6b2n/plugins/behaviour/compat6/services/provider.php on line 38

@exlemor You can test as follows:

On a clean 5.4-dev or latest 5.4 nightly build or 5.4-beta1, enable "Debug System" and set error reporting to maximum in global configuration. Then in the Joomla Update Component, change update channel to custom URL and use the URL of the 6.0 nightlies: https://update.joomla.org/core/nightlies/next_major_list.xml . You might have to disable the Joomla 5 compat plugin before the update.

Result:

Do the same with the same starting conditions but this time use the custom update URL from this PR: https://artifacts.joomla.org/drone/joomla/joomla-cms/6.0-dev/45998/downloads/87556/pr_list.xml

Result:

I have tested this item ✅ successfully on 6dae38c

Details on how to test and the result see in my previous comment.

I have tested this item ✅ successfully on 6dae38c

RTC

@exlemor You can test as follows:

On a clean 5.4-dev or latest 5.4 nightly build or 5.4-beta1, enable "Debug System" and set error reporting to maximum in global configuration. Then in the Joomla Update Component, change update channel to custom URL and use the URL of the 6.0 nightlies: https://update.joomla.org/core/nightlies/next_major_list.xml . You might have to disable the Joomla 5 compat plugin before the update.

Result:

Do the same with the same starting conditions but this time use the custom update URL from this PR: https://artifacts.joomla.org/drone/joomla/joomla-cms/6.0-dev/45998/downloads/87556/pr_list.xml

Result:

Thanks @richard67 but I just got freed now and it is already RTC - you guys are fast ;) - The Testing Instructions needed a bit of an update for me to be able to get the expected results.

Thanks for all of your collective hard work.

thank you @laoneo much appreciated