Wrong structure definition; Contact your system administrator

What causes this issue?

Defined R/3 structure or S/4 HANA structure description does not exists
or it is not set correctly.

System Response

Conversion of classified object key from R/3 to S/4 HANA is not
possible.
System does not convert the value.

How to fix this error?

Review the entries in MFLE_XPRA_MAPPER table.
In case of not existing DDIC structure(s) import the missing entries or
define them in the Data Dictionary.
In case of wrong R/3 or S/4 HANA field name definition correct the
definition.

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.