Please choose a valid source system.

What causes this issue?

You can only enter a source system that is supported by <LS>Central
Finance</>.

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?

Enter a source system that is supported by <LS>Central Finance</>.

Procedure for System Administrators

For a list of possible source systems allowed in <LS>Central Finance</>,
please check the Customizing activity <LS>Define Technical Settings for
Business Systems</>.

Error message extract from SAP system. Copyright SAP SE.