Created attachment 1085844 [details] server log Description of problem: (See steps and results.) Version-Release number of selected component (if applicable): 6.2 ER4 Steps to Reproduce: 1. Open Project editor for any random project, switch to Knowledge bases and sessions. 2. Add a new kbase with name 'k1'. 3. Add a new ksession with the same name, 'k1', to this kbase. 4. Save the changes and look into the server log. Actual results: Everything seems fine in the GUI, but server log contains the following message: ERROR [org.kie.workbench.common.services.backend.builder.BuildServiceImpl] (EJB default - 10) null: java.lang.NullPointerException Expected results: Either everything is fine and server log is clean as well or there is the error logged (correctly) and the user is warned in the GUI that same names are illegal.