Step to reproduce

• On DX Core or CE 6.3 version, open Security app
• Select user "eric" and click "Edit user" action
• Set new password for the user
• Click button "Save changes"

Second case is it can't login with user eric also, it might be the same root cause.

Actual result

• Error message "User cannot be created. No user manager with realm name admin is defined." pop up in the UI, check the error logs in the attachment.
• Cannot login with non-system user like eric, peter, tina

Expected result

• User's password should be changed successfully
• Be able to login with non-system user

More info: It works on Magnolia 6.2.x version

Discovery:

This configuration that is needed for admin realm was removed on master branch
https://git.magnolia-cms.com/projects/PLATFORM/repos/main/browse/magnolia-core/src/main/resources/mgnl-bootstrap/core/config.server.security.xml?at=refs%2Fheads%2Frelease%2F6.2#106
Needs to be brought back by security module?

caused by https://git.magnolia-cms.com/projects/PLATFORM/repos/main/commits/b96443424ef6242573ab001b782d2a100562c3be#magnolia-core/src/main/resources/mgnl-bootstrap/core/config.server.security.xml

Note: revert https://git.magnolia-cms.com/projects/PLATFORM/repos/main/commits/b96443424ef6242573ab001b782d2a100562c3be#magnolia-core/src/main/resources/mgnl-bootstrap/core/config.server.security.xml