Need help with setting up a Post user registration action

  • Failed Post User Registration Hook

  • Description

ArgumentError on post-user-registration: Must provide a domain

I keep getting this error even though I have provided the domain of my application in my action

and I am using a modified version of the code given in this blog post:

Please let me know how I can fix this

Hi there @AdmiralBot!

Do you mind sharing your exact Action code here so we can take a look and see what might be the issue? I’d like to try and reproduce it as closely as possible.


hey I am attaching my code here please let me know what I need to fix

exports.onExecutePostUserRegistration= async (event, api) => {
const namespace = “”;

const ManagementClient = require(“auth0”).ManagementClient;

const management = new ManagementClient({
domain: event.secrets.domain,
clientId: event.secrets.clientId,
clientSecret: event.secrets.clientSecret,
scope: “read:roles create:roles update:roles”,

const defaultRole = { id :‘rol_R0LEZGNx7GPlmKXe’};
var data = { “users” : [ event.user.user_id]};

try {
if (event.authorization){
api.idToken.setCustomClaim(${namespace}/roles, event.secrets.defaultRole);
api.accessToken.setCustomClaim(${namespace}/roles, event.secrets.defaultRole);
await management.roles.assignUsers(defaultRole, data);
} catch (e) {


Thanks for sharing your code!

This is a bit trickier than I expected given a couple things:

  • Post registration actions do not have access to the event.authorization object and therefore this needs to be broken out into a Post-login action.

  • You’ll need to introduce login into the Post-login action in order to account for the fact that you want to include the event.secrets.defaultRole if it’s the user’s first login and event.authorization.roles if it’s any subsequent login. The reason being the role assigned in the Post-registration action will not be available via event.authorization.roles on first login.

Here’s a Post-registration and Post-login action that in unison are working for me:

Post User Registration:

exports.onExecutePostUserRegistration = async (event, api) => {

const namespace = "";

const ManagementClient = require("auth0").ManagementClient;

const management = new ManagementClient({
domain: event.secrets.domain,
clientId: event.secrets.clientID,
clientSecret: event.secrets.clientSecret,
scope: "read:roles create:roles update:roles"

const params = { id : event.user.user_id};
var data = { "roles" : ['your_default_role_id']};

management.assignRolestoUser(params, data, function (err) {
  if (err) {
    // Handle error.
  console.log(`User ${} successfully assigned default role.`)
  // User assigned roles.

Post Login:

exports.onExecutePostLogin = async (event, api) => {
const namespace = ""
//if this is the users first login, use the role hardcoded in event.secrets.defaultRole
 if (event.stats.logins_count == 1) {
    api.accessToken.setCustomClaim(`${namespace}/roles`, event.secrets.defaultRole ),
    api.idToken.setCustomClaim(`${namespace}/roles`, event.secrets.defaultRole )
  } else {
  //if this isn't the users first login, assign roles from event.authorization. 
  if (event.authorization) {
    api.accessToken.setCustomClaim(`${namespace}/roles`, event.authorization.roles ),
    api.idToken.setCustomClaim(`${namespace}/roles`, event.authorization.roles )

Hope this helps!

hey thanks for the response. So i will need to use 2 actions here, one in the post registration flow and one in the post login flow am I correct??

Also it is showing this error for the post login action:

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hey there @tyf is there any update??, the code you shared also shows the same error

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Hey @AdmiralBot - That error looks to be related to a Post User Registration Hook as opposed to a Post User Registration Action. Are you able to confirm whether or not that’s the case?

You’ll need to add defaultRole to the actions events.secrets in order to resolve these errors - This is required for an initial login by a user as the role is not yet available in event.authorization.roles.

How do i add default role to event.secrets??

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In this example, I am just using the string defaultRole role in event.secrets and adding it as a custom claim to tokens for the user’s first login only. Once a user logs in again, the defaultRole is added via event.authorization.roles - Using the defaultRole via event.secrets is acting as a sort of placeholder in order to have the role in tokens on first login.

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