NextAuth Invalid Grant Error

[amol]

We have a user running into a 502 gateway. We are using NextJS, and NextAuth. In our web app logs, we can see a:

error: OPError: invalid_grant (Invalid authorization code)

Auth0 history shows a successful login and exchange

[rueben.tiow]

Hi @amol,

Thanks for reaching out to the Auth0 Community!

It seems that you may have failed to exchange your authorization code for an access token possibly due to an invalid grant.

In this situation, could you please make sure that the application making the request has the Authorization Code grant enabled? See Update Grant Types.

Let me know how this goes for you.

Thanks,
Rueben

[amol]

Hi @rueben.tiow

Yes it is enabled. I’d like to reiterate this issue is happening for only one user out of hundreds. We are not sure if there is something wrong with their auth0 account.

I suspect this public forum may not be the place to debug the issue with this specific user but let me know how I can share that information.

[rueben.tiow]

Hi @amol,

Thanks for the update and confirmation.

I have just tried to reproduce this issue and was able to do so by passing in an invalid authorization code. See below:

Seeing that, could you verify the user’s auth flow is failing to exchange the authorization code for an access token? You can check your Auth0 logs for the feacft log event type code.

[amol]

@rueben.tiow Yes, I do see that in our logs

[amol]

@rueben.tiow what would be the next step to debug?

[amol]

It turns out we had to increase the NGINX buffer size

[rueben.tiow]

Hi @amol,

Thanks for the replies, and for sharing your solution with the rest of the Community!

If you have any further questions, please feel free to reach out to us again.

Cheers,
Rueben