Account & in company code & is not a reconciliation account

What causes this issue?

G/L account &v1& in company code &v2& which is to be updated when
posting to the customer or vendor is not defined as a reconciliation
account.

How to fix this error?

Depending on the cause of the error you can
change the master record of the above-mentioned account and mark it as
a reconciliation account
change the customer or vendor master record and enter a different
reconciliation account there
for special G/L transactions, change the allocation of reconciliation
accounts when configuring special G/L transactions.

Error message extract from SAP system. Copyright SAP SE.