&4 No transaction direction is assigned to transaction type &1

What causes this issue?

In Customizing at least one transaction direction must be assigned to a
transaction type. This is not the case for the transaction type
involved.

System Response

Processing cannot be continued.

How to fix this error?

Correct the error in Customizing.

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.