What causes this issue?

You are suing an old transaction.

System Response

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

How to fix this error?

The transaktions VT01, VT02, and VT03 are old and have been replaced
with new transactions VT01n, VT02n, and VT03n as of Release 4.6A.
Only use the old transactions for batch input.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.