Users receive the error message User is invalid: Email: has already been taken when they try to sign in via JWT.
- Account is leveraging JWT for user role.
- An external id is being passed in with JWT payload.
The error message: User is invalid: Email: has already been taken - typically means that the external ID being passed in the JWT payload is already taken by a user in your Zendesk with a different email address. The error is caused by the external ID and email address appearing on two different user profiles.
To resolve this issue, merge the end user profiles. Additionally, verify that the JWT identity provider has the same email addresses associated with the same external ID.