The result is expected, because Joomla 4 does not have the class JEventDispatcher. The Search component, com_search is part of Joomla 3 and it is not required in Joomla 4. Joomla 4 uses Smart Search, com_finder.

It is better to post these types of issues first to the Joomla! forum, https://forum.joomla.org.

"The Search component, com_search is part of Joomla 3 and it is not required in Joomla 4. Joomla 4 uses Smart Search, com_finder." hmmm

Why is it not then removed in Joomla 4 and Joomla 5?
How can it then be possible to add the "Module Search (=com_search) is added" if it not work in Joomla 4 & 5? If so serious bug.

Maybe releated to issue I have here too https://issues.joomla.org/tracker/joomla-cms/42617

com_search was decoupled from Joomla 4. Version 4.1.0 is available (not tested): https://github.com/joomla-extensions/search/releases

Hellom
Thanks for all replies.
When: 'The Search component, com_search is part of Joomla 3 and it is not required in Joomla 4. Joomla 4 uses Smart Search, com_finder.'
it should be removed from the repository. A module which is not working/supported anymore should not be included.
And I reported here in the issue tracker, because it is a (serious) bug and not a forum question.
(remark: thera are more third party Joomla 4 components using JEventDispatcher e.g. JCE; so all these components are getting problems I guess).

Regards,
Peter

Remerk 2: I upgraded from Joomla 3.10. May that's why com_search is there. It is not removed during upgrading.
May be it is an idea to check obsolete modules and remove them.

Regards,
Peter

Remark 3: or offer an update of com_search. The https://raw.githubusercontent.com/joomla-extensions/search/main/manifest.xml does offer version 4.0.1-dev, but that is nog visible in the standard update path.

Proposal to enhance Update procedure:

• make list of deprecated function (e.g. JEventDispatcher, JRequest)
• prior upgrade test scan all source code of website and inspect modules having obsolete functions
• propose to disable or remove identified modules/plugins/extensions and name/notify them.
• Additionaly send names with versions to Joomla database to mark these modules as incompatible for upgrade for others (users and developers) to know too; this database could be more reliable source for flagging modules not with warning, but with exact info/problem for no-go of upgrade with them enabled.
• even if user decides not to remove these blamed modules/plugins/extensions, disable them during upgrade.
  This would safe head aches of less experienced web admins.

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  _{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/42625.}

This feature suggested here: https://issues.joomla.org/tracker/joomla-cms/42626

As has been written here, there is an update to com_search which fixes this issue. Closing this issue.