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OAU-251 - Unauthorized for this grant type
Tags: authentication
Feb 28, 2024 at 6:59am   •   2 replies  •  1 likes

I'm trying to update my app to use JWT. I'm using the C# API. It seems like a one line change, but I'm getting the error

"errorCode" : "OAU-251",

"message" : "Unauthorized for this grant type"

2 Answers
answered on Feb 29, 2024 at 7:19am  


I am facing exact same error "OAU-251", I have re-activated my sandbox account for this trial before I do change in production. But I am stuck.

what I did:

1) Reactivated the Sandbox - New number was provided as it was expired.

2) Created one JWT and restricted it for only one App by providing client ID

3) Attempted JWT authorization and got "OAU-251" error.

4) I am still able to use Password flow to Auth. But SMS is stopped so cannot test! :(

If Auth type change is required, then please share the page link from where to do that.

on Feb 29, 2024 at 8:51am   •  0 likes

Finally, it worked. Under App/Settings I changed Auth Setting to JWT auth flow and after 10-15 minutes it worked. But the Password auth flow option is gone now!!

answered on Feb 28, 2024 at 7:26am  

Try again after 5 or 10 mins after you changes the auth type.

If the problem persists, give me the app client id so I can enable both password flow and JWT so that you can continue support the password flow until March 31st while you are testing the JWT flow.


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