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Advocate II
Advocate II

Custom Connector OAuth Redirect

I am creating a custom connector to an internal API which requires OAuth security.


On the security page, I enter all the information as needed and when the connector is saved, it will general a Redirect URL (, which is then added to the valid call back list on the Azure App Registration list.


However, when I go to test the connector, I get the error AADSTS500113: No reply address is registered for the application


Digging a bit deeper, in the URL of the error page, I can see that there's an embedded redirect (in red)


When this is added to the App Registration valid redirect list, it then goes the that URL but this results in a 404 error page.


The connector "saves" OK, but it cannot be tested, and when it is implemented in a flow, it fails with a 401 error code and the error message "Invalid or missing token"


So, this is a bit of a show-stopper at the moment as i cannot create custom data connectors.

Power Automate
Power Automate

You just need

For example


Screenshot 2020-11-03 115750.png


Can you please share similar snapshot from you app?

Advocate II
Advocate II

I did have in the redirect list... However, Power Automate is not redirecting back to that location, it is redirecting to (which returns a 404 error)


I have gone through Microsoft Support and have since spoken to a team member and whilst I do not believe the underlying issue is resolved, I do have things working now.

Power Automate
Power Automate

Great to know that you are unblocked. I am following up on why global redirect didnt work for you. Will post on this thread once i have more info.

Regular Visitor

@shyamsu any updates available? I am also running into this problem where the redirect is not using the global URI, and is instead going to where it gives a 404.

New Member

Did anyone ever figure this out? I'm having the exact same problem. 

IIRC I think the issue was that as the Custom Connector uses Client / Secret to communicate to underlying API, the user account of the connection reference to the custom connector was not authorised to use the [Client] App Registration 




Thanks very much for the reply. I think I finally got all of the correct settings to get the API working. Keeping my fingers crossed that it keeps working. I'm actually thinking of creating a YouTube video showing how I did it. I'm using the Constant Contact API and I couldn't find an example of how to do this anywhere. Was driving me nuts. 

Regular Visitor

how did you get it to work?

New Member

Well, I sort of did and didn't. The problem, specifically with Constant Contact, is that they don't support the necessary OAuth flow for unattended authentication. This causes the connection in Flow to break after just a couple of hours and then I have to sign on again manually to re-establish a working connection. 


The specific problem I was having with just getting the call to work is that my Base URL setting needed a trailing slash, so instead of /v3 it should have been /v3/. Really simple problem, but there were zero helpful errors generated that I could find that would point to the issue. 

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