Object & has incorrect object type

What causes this issue?

Object &V1& in client &V2& does not belong to object type KL (cost
center/activity type). However, an entry exists for this object in the
table to be converted COKL in ledger &V3&.

System Response

The conversion report &V4& can only process cost center/activity type
objects; the transaction figure found cannot therefore be converted.

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?

Error message extract from SAP system. Copyright SAP SE.