If you already have the functional currency setup for a company, but the log tells you that you do not, please verify that the index is correct. As always, make sure you have a backup prior to running any scripts against the database.
select funcridx, * from dynamics.dbo.MC40200 --look for the currency setup as functional currency
select funcridx, * from [COMPANY].dbo.MC40000 --verify that the funcridx matches what as found above
Update [COMPANY].dbo.mc40000 set funcridx = [Correct index] --if not, update it