Xero transaction - “JSON for post data was invalid, Error converting value” error

  • 12 December 2021
  • 3 replies

I’m trying to set up a zap between Excel and Xero to make it easier to enter them on a monthly basis.  The Excel side works, and finding/creating a contact in Xero works, but when I try test the creation of the bank transaction I get an error saying that the JSON for post data was invalid, Error converting value (Contact value) to type ‘System.Guild”.  Does anyone have any suggestions?


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3 replies

Userlevel 7
Badge +14

Hi @mmitchell 

Try mapping the Contact ID from the previous step instead of the Contact name.


Thanks @Troy Tessalone 

I’ve just tried that and if I use the contact First Name & Last Name it tells me the contact ID is missing.  If I use the Company it gives me the same error.

Userlevel 7
Badge +14


Please post screenshots with how your Zap steps are configured.

NOTE: The expected Contact ID is likely a number.