Transport of customizing changes is not configured

What causes this issue?

You want to record your changes in request &V1& with transport target
&V2&. However, the transport routes in this SAP System are not
configured to transport Customizing changes from this client.
If you do not stick to the configured transport routes, you may cause
inconsistencies between the systems in your system landscape.

How to fix this error?

You can continue editing, or you can choose another request to record
your changes in. Choose a request without a transport target.

Procedure for System Administrators

Customizing changes in this client are transported as standard if a
consolidation route is set up for the standard transport layer of this
system or client.
To do this, use the transport route editor of the Transport Management
System.

Error message extract from SAP system. Copyright SAP SE.