Direct change of construction type is not allowed

What causes this issue?

Synchronous maintenance of material number and construction type are
intended for this type of equipment in Customizing, or to be precise:
If the material number is maintained, then the construction type must
have the same value.

System Response

If both values are maintained synchronously, no direct change of the
construction type is allowed.

How to fix this error?

Changes to synchronously maintained values are only possible using the
material number. If you do not want synchronous data storage, then you
should change the type of the equipment or change the settings in
Customizing.

Error message extract from SAP system. Copyright SAP SE.