Activation group &1 is assigned to different mass activator types

What causes this issue?

The assigned objects of the activation group belong to different mass
activator types. This is not allowed, because an activation group can
bundle only objects of the same mass activator type.

System Response

The system aborts generation.

How to fix this error?

Correct the assignment by changing the mass activator type of the
relevant objects for that you want to use mass activation.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.