The Error creating Contact: Bad Request being returned by HubSpot is an INVALID_OPTION error that is thrown when the Property values were not valid. In many cases, this is caused because the State that's being synced from Quoter to HubSpot doesn't match the State/Region defined in HubSpot.
We find this happens when the State/Region Field Type has been changed from the Single-line text HubSpot Default to the Dropdown Select. Unless all of the State Options are present in this converted Dropdown Select, the above error message will be returned when Quoter pushes data to HubSpot.
This can be resolved by navigating to Settings > Properties where they can use the search feature to find State/Region to edit the Field Type to Single-line text as per the screenshot below:
The failed attempt can be manually re-attempted once the above change is made or Quoter will automatically re-attempt to push the data provided the maximum number of allowed attempts have not been exceeded. Please contact our Partner Success team should you still encounter issues.