How do I build a custom connector for Power Automate?

  • 13 September 2021
  • 2 replies


I’ve been trying to build a custom connector from Powerautomate and it is not authenticating me. I have tried both Post authentification using Json as well as OAuth2.9 from Postman and they were both successful. 

Issue #1:
I’ve tried the api key authentication but don’t know where to find the API key for acumatica? Can someone let me know where to find it please?

Issue #2: 

In lieu of the API Key authentication, I tried OAuth2.0 but keep getting the error: 
“The client application is not known or is not authorized”

Can you please confirm that my URLS are correct, I need the following fields:


Client id: generated in acumatica under connected application

Client Secret: generated in acumatica under connected application

Authorization URL:

Token URL:

Refresh URL:

Scope: api

2 replies

Userlevel 1

Hi @ekermani


While I have not used Power Automate, I’m happy to share a workflow process we have had success with using Zappier. 


First, we set the Acumatica side Connected Applications OAuth 2.0 Flow to ‘Resource Owner Password Credentials’ and generate a Shared Secret.



Next, call the ‘Token URL’ you mentioned in your post, passing the following in the request body in an x-www-form-urlencoded format:

  • grant_type: ‘password’
  • client_id: <The Client ID of your Connected Applications entry in Acumatica>
  • client_secret: <The Shared Secret>
  • username: <An Acumatica Username>
  • password: <The password for the above Acumatica username>
  • scope: ‘api’


If the setup is good, you will get a response that looks like this:



Now that you have the access_token, you can use it to send your follow up requests to Acumatica.  You can do this by adding the following to your request headers:

Authorization: Bearer <your access token>



More information can be found here under the ‘Authorizing Client Applications to Work with Acumatica ERP’ section:


Hi Stephen, 
Thank you for your response. I did eventually figure out the OAuth2 from power automate to Acumatica but the parameters that Powerautomate sends acumatica for authentication is different and not in the correct format. 
see below:


Authorization Code Flow sample:








What powerautomate sends: 

Invalid flow for client: AuthorizationCode


  "ClientId": "******************************************************************t",

  "ClientName": "Postman2",

  "RedirectUri": "",

  "AllowedRedirectUris": [



  "SubjectId": "unknown",

  "ResponseType": "code",

  "ResponseMode": "query",

  "Flow": "AuthorizationCode",

  "RequestedScopes": "",

  "State": "*************************************************",

  "Raw": {

    "client_id": "****************************************************",

    "response_type": "code",

    "redirect_uri": "",

    "scope": "api offline_access",

    "state": "******************************"




Can you suggest a method to go around this? Thank you


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