Enter info record without material

What causes this issue?

You entered a <DS:GLOS.purchasing_info_record>purchasing info record</>
with a material master. This is not acceptable for external processing
operation since you are purchasing a service or activity and not a
material.

How to fix this error?

Enter a purchasing info record without a material master that has an
info record category 0 (normal) or 3 (subcontracting) subcontractor
purchasing info record (type "3").
<ZH>Note:</>
If, when you are searching for a suitable info record, you select the
search help "info records for external processing", the system
automatically displays only the info records without material masters
that have the info record category 0 or 3.

Error message extract from SAP system. Copyright SAP SE.