Equipment &1 is already locked by user &2

What causes this issue?

INCLUDE 'SPERREN1' OBJECT DOKU ID TX LANGUAGE E

System Response

INCLUDE 'SPERREN2' OBJECT DOKU ID TX LANGUAGE E

How to fix this error?

INCLUDE 'SPERREN3' OBJECT DOKU ID TX LANGUAGE E
Special case;
In a contract you selected an item, selected the object list using the
menu path 'Extras -> Technical Objects', and entered a new piece of
equipment there or selected a pre-existing piece of equipment. A double
click takes you to the display of the equipment master, and now you want
to change to the change mode.
However, this step is not allowed for the following reason:
When equipment is installed in the object list - depending on the
Customizing setting - a user status is set. For this change of the user
status, the equipment must be locked so that other changes that change
the status again cannot be made at the same time.
Equipment that already exists in the object list are then locked for
changes, as the user could possibly want to delete them from the object
list, thus changing the user status.
In such a case, you cannot change the equipment master record until you
have left the contract.

Error message extract from SAP system. Copyright SAP SE.