This article explains the errors that might occur on the dispatch page.
Errors that can be resolved:
PartnerRateLimitExceeded
Xero has received too many requests in a short period of time and needs the requests to slow down - try again in a while.
Xero authorisation failure –(invalid_grant)
This error occurs when a sync refresh token expires and can be fixed by disconnecting and the reconnecting to Xero.
Contact Uptick when:
PostDataInvalidException
we need to look into this one, so send us a support ticket.