It is important to note that all the amounts, whether entered or imported, are converted and stored in 3 currencies (transaction currency, company currency and reporting currency). The accounting operation can only be processed if the two exchange rates that are required for this operation are entered.
In the case of exchanges between IN currencies, the exchange rates are defined automatically in the currency table. In the other cases, a rate must have been defined at the date of the journal or at an earlier date (see the Currency rates documentation).