# 20153: Invalid Issuer Or Subject

Log Level: ERROR

## Description

The issuer or subject of the JWT provided to the Twilio API was invalid.

### Possible causes

* The issuer is missing from JWT
* The issuer entity is suspended in Twilio.
* The subject is missing from JWT
* The subject entity is suspended in Twilio.
* The issuer and subject are not related.

### Possible Solution:

* In case of Public Key Client Validation, make sure the account and the API key are valid and not suspended.
* For the details on JWTs used as part of Public Key Client Validation, see [the documentation](/docs/iam/pkcv/quickstart)
* To check whether the JWT is structurally correct, you can use the tools available at jwt.io.