One and a half year later, same exception occurred to me.

org.hibernate.StaleStateException: Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1

I have a deadline to catch, and my code is all wrapped up in Spring and Maven, so no time to make a proper test case. But with the attached very simple use case reproduction of the bug will only cost a minute or two. Using hsqldb the code runs smoothly.

A quick look in my pom.xml shows the following relevant jars:
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>4.3.7.Final</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.31</version>
</dependency>
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
<version>2.2.9</version>
</dependency>