Postings can only be made to G/L acct. & in curr. &

What causes this issue?

The currency of the <GL:G/L_account>G/L account</> differs from the
currency of the specified <GL:company_code>company code</>.
This <GL:account_assignment>account assignment</> is therefore not
possible.

How to fix this error?

Check whether you have entered:
The right <GL:purchasing_organization>purchasing organization</>
The right G/L account

Error message extract from SAP system. Copyright SAP SE.