Error
Invalid VAT number. The number must be entered in the following format.
(Translation:)
Ongeldig btw-nummer. Het nummer moet in het volgende formaat worden ingevoerd
Cause
The VAT number of the customer that you are trying to synchronize is incorrect.
Solution
Use this link to check the VAT number validity based on ExactOnline's format. Change the customer's VAT number and try running the synchronization again. If needed, use the corresponding export step.