Port '&' already exists or a system error occurred when inserting

What causes this issue?

An error occurred during an attempt to save a new port on the database.

System Response

The port cannot be inserted.

How to fix this error?

Depending on the cause, you must do the following:
You are in the online transaction for port maintenance and in the mean
time another user has created a port of the same name. In this case,
please cancel the action and refresh the port tree display. The new
port then appears. If you want to create a further port, please choose
a different name.
System error on the database! In this case, please notify your system
administrator.

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.