Object type not supported: &1 &2

What causes this issue?

A program code called OBJKNR converter for an Object type which is not
supported from the OBJKN converter.

System Response

Object type not supported

How to fix this error?

Inform your system Administrator

Procedure for System Administrators

This error is received if a non-flat structure is parsed to the OBJKN
converter Method(cl_ofle_converter->bapi_tables_conv_tab) or the
elementary field is not a supported data type. (e.g. char fields are not
supported).
If the message is raised from SAP coding<(>,<)> open a SAP incident. If
the message is raised within non SAP coding contact responsible
developer/partner.

Error message extract from SAP system. Copyright SAP SE.