Spring: tests extends AbstractTestNGSpringContextTests fail when upgrading Spring 3.0 to 3.1

I'm using Spring 3.0.5 (not spring boot) to implement web controllers over Tomcat server. The project initial version was running on Spring 3.0.5, and I had to upgrade it to 3.1 (for Validation purposes).

After the upgrade everything is working fine, except all tests derived from AbstractTestNGSpringContextTests that fail.

Is it something typical in upgrade processes?

Thanks