Enter only material number or equipment number

What causes this issue?

You entered both a material number and an equipment number. Therefore,
the system does not recognize whether to determine a material BOM or
an equipment BOM.

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 either a material number or an equipement number, depending on
whether you wish to reference a material BOM or an equipment BOM.

Error message extract from SAP system. Copyright SAP SE.