# Troubleshooting

## Log messages

This section discusses certain log messages you might see from Hibernate and the "meaning" of those messages. Specifically, it will discuss certain messages having a "message id", which for Hibernate is always the code `HHH` followed by a numeric code. The table below is ordered by this code.

Explanation of identified log messages

Key | Explanation
--- | ---
HHH000002 | Indicates that a session was left associated with the org.hibernate.context.internal.ThreadLocalSessionContext that is used to implement thread-based current session management. Internally that class uses a ThreadLocal, and in environments where Threads are pooled this could represent a potential "bleed through" situation. Consider using a different org.hibernate.context.spi.CurrentSessionContext implementation. Otherwise, make sure the sessions always get unbound properly.
HHH000408 | Using workaround for JVM bug in java.sql.Timestamp. Certain JVMs are known to have a bug in the implementation of java.sql.Timestamp that causes the following condition to evaluate to `false`: `new Timestamp(x).getTime() != x`. A huge concern here is to make sure you are not using temporal based optimistic locking on such JVMs.