Getting Error “EntityManager is Null” in JPA. How to Never Face It Again

The subtle CDI mistake that breaks Jakarta Persistence (formerly, JPA or Java Persistence APIs)

Non-members can read this post from here.

Why did your EntityManager suddenly go null?

Got the deadly NullPointerException when calling createNamedQuery() on a Jakarta Persistence? You are not alone.

Did you get the deadly NullPointerException when calling createNamedQuery() on a Jakarta Persistence or JPA EntityManager? This error can lead to unexpected application behavior and can be a nightmare to debug. You are not alone.

CDI or Context and Dependency Injection, is a powerful Jakarta EE (formerly, Java EE) standard that allows you to manage the lifecycle of your beans and inject dependencies.

Issues with constructors are common when working with CDI and JPA. Let me explain what likely happened and provide some best practices to avoid similar problems in the future.

What likely caused this error — “EntityManager is null”?

If you have encountered the error :

Cannot invoke 
"jakarta.persistence.EntityManager.createNamedQuery(String, java.lang.Class)" 
because…