xwiki 11.5 - Failed to execute the [velocity] macro

Hi,

I get an Error on sending an page/article into a workflow step (doenst matter which step).
I used the Publication Workflow App before, so I am aware of setting groups draftig Space etc... With other (older) installations, I dont meet this Issue.

After the click "start wokflow",the page says:

—
Failed to execute the [velocity] macro. Cause: [class [Ljava.lang.Object; cannot be cast to class [Ljava.lang.String; ([Ljava.lang.Object; and [Ljava.lang.String; are in module java.base of loader 'bootstrap')]. Click on this message for details.
—

By clicking "details", the Sourcecode of /PublicationWorkflow/Script will be displayed.

By reloading the page, it says: "An error occurred while executing the workflow action." (Translated from german)

By changing the page and comming back, the next steps will be shown in the Workflow Area, but if I click on a next Step, the same error will occur.

Does anyone have an idea how to solve this?

Thanks a lot!