If you are seeing the error "There was an error when communicating with DHL Parcel UK: pickupAccount is invalid, account is on stop." when trying to book a shipment with DHL Parcel UK, it means that there is a problem with your DHL account. This can include overdue invoices, or that your account has been closed.
In order to resolve this, you will need to get into contact with your account manager at DHL (feel free to CC [email protected]). They will be able to outline the reasons why your account is not active, and they will be able to help you get it up and running again.
If DHL have confirmed that your account is active and you are still seeing this error, please get in touch with support.