Ladislav Lenčucha

Two things - you have to enable JWT authentication in Zendesk setup and make sure you initialize Zendesk SDK properly (you need to use the identity which expects customer identifier/token)

Usually the issue is with the JWT you return. I think I managed to get all the problems that might occur:
- undefined custom field
- inconsistent identity (different id with same email already existed in Zendesk)
- incorrect signature
- incorrect language code

Sadly you can get the explanation from Zendesk support only, which has 2-5 days reaction time.

Nope, field must be present and non-empty. However, in case of JWT authentication, you can provide also external_id which will be used for customer matching instad of email. The primary identity is then in your hands.

It's a shame there is no "Test it now" button in the Mobile SDK App Setup page. One where I could provide "unique_id" and get some kind of feedback whether the endpoint is reachable, returns correct JWT (content-wise and signature-wise).

Would it be possible to have this? It would definitely help decrease number of support tickets on your side.

How is user_identifier_provided_by_the_app used by Zendesk? Do you create a customer/user based on user identifier or is it based on returned email and phone from jwt token?

Providing simply the user identifier is not secure at all as mentioned by Colbey W. We're thinking to provide another token (retrieved by mobile app) which will be accepted by our jwt service and return the data based on the token.

Thanks!