No cost collector has been defined for order &

You worked on order &V1&. No cost collector has been defined for this
order. You can check this by displaying the order in table AUFK.
Display the cost collector when you call up this table.

System Response

Posting or selection of CO objects is not possible without a cost
collector.

How to fix this error?

The error is probably linked to importing Release 1.2A and converting
the CO data. The SAP System is functional again once the update level
is imported and the data is sucessfully converted.
If the termination occurs for any other reason, an internal system
error has occurred. Contact the SAP hotline service.

Error message extract from SAP system. Copyright SAP SE.