The code does not comply with the format 1[0-9][0-9][0-9].]
Translation: De code voldoet niet aan het formaat 1[0-9][0-9][0-9].]
The integration is trying to create a debtor or creditor in Twinfield but is unable to do so because the customer number from the source file does not meet the required format.
To solve the issue, the debtor mask format of 1[0-9][0-9][0-9] needs to be changed to * (see screenshot).
Go to Twinfield > Settings > Administration settings > Dimension types > Debtors (DEB) to make this change.