Failed Signup - Extensibility internal error

I had a couple of users be unable to signup and I see this error in the Auth0 logs for both of them.

The response we were getting from Auth0 was:
{“statusCode”:400,“error”:“Bad Request”,“message”:“Sandbox Error: Internal server error”}

And the Auth0 logs had records for type=“Failed Signup” description: “Extensibility internal error” for both of these users.

I have no hooks setup. I do have some rules setup on the login flow, but not the Post/Pre User Registration flow.

They seem to be the only users having this issue and the signup action has been working for others and I was able to activate their accounts using the same url. These users are on the same network, so I’m thinking it has to do with how their network is setup. After I activated their accounts on my side though, they’ve been able to login, so whatever the issue is seems to just affect sign up.

Hi @christine.david,

Welcome to the Auth0 Community!

Whenever a user signs up, they automatically log in by default. Because of this, your Rules may be responsible for triggering an extensibility internal error.

Could you please test your Rules to ensure they do not throw an unintentional error?

You may also need to use the Real-time Webtask Logs Extension to monitor these logs.

Let me know how this goes for you.


I can try turning on those logs.

But the reason I don’t think it’s the login rules is because these users were able to login after I went through the sign up flow for them. Why would the login rules trigger this error only for the sign up flow and not the login flow? And why was I able to go through the sign up flow for their users and not trigger the error if it really was the rule being broken? There seems to be something else going on.

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I just realized those sign up requests happened during the US-3 outage that happened today.

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Hi @christine.david,

Thanks for the responses.

I’m glad to hear that your users can now sign up as usual and that the issue related to an outage in the US-3 region has been resolved.

Please let us know if anything else we can do to help.


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