Happens for a small percentage of the registrations. Our installations have between 3 and 6 categories each, and this error seems to happen on a registration update.

2016-09-08 10:35:07,230 WARN [org.hibernate.engine.jdbc.spi.SqlExceptionHelper] (EJB default - 10) SQL Error: 0, SQLState: 23505
2016-09-08 10:35:07,231 ERROR [org.hibernate.engine.jdbc.spi.SqlExceptionHelper] (EJB default - 10) ERROR: duplicate key value violates unique constraint "installation_category_pkey"
Detail: Key (installation_id, category_id)=(78bf2331-2ce6-400b-a4cd-7a770c9598c5, 55) already exists.
2016-09-08 10:35:07,231 INFO [org.hibernate.engine.jdbc.batch.internal.AbstractBatchImpl] (EJB default - 10) HHH000010: On release of batch it still contained JDBC statements
2016-09-08 10:35:07,263 ERROR [org.jboss.as.ejb3.invocation] (EJB default - 10) JBAS014134: EJB Invocation failed on component ClientInstallationServiceImpl for method public abstract void org.jboss.aerogear.unifiedpush.service.ClientInstallationService.addInstallation(org.jboss.aerogear.unifiedpush.api.Variant,org.jboss.aerogear.unifiedpush.api.Installation): javax.ejb.EJBException: javax.persistence.PersistenceException: org.hibernate.exception.ConstraintViolationException: could not execute statement
at org.jboss.as.ejb3.tx.CMTTxInterceptor.handleExceptionInOurTx(CMTTxInterceptor.java:190) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInOurTx(CMTTxInterceptor.java:275) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.as.ejb3.tx.CMTTxInterceptor.required(CMTTxInterceptor.java:340) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.as.ejb3.tx.CMTTxInterceptor.processInvocation(CMTTxInterceptor.java:239) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ejb3.component.interceptors.CurrentInvocationContextInterceptor.processInvocation(CurrentInvocationContextInterceptor.java:41) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ejb3.component.invocationmetrics.WaitTimeInterceptor.processInvocation(WaitTimeInterceptor.java:43) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ejb3.security.SecurityContextInterceptor.processInvocation(SecurityContextInterceptor.java:95) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ejb3.component.interceptors.ShutDownInterceptorFactory$1.processInvocation(ShutDownInterceptorFactory.java:64) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ejb3.component.interceptors.LoggingInterceptor.processInvocation(LoggingInterceptor.java:59) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ee.component.NamespaceContextInterceptor.processInvocation(NamespaceContextInterceptor.java:50)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ejb3.component.interceptors.AdditionalSetupInterceptor.processInvocation(AdditionalSetupInterceptor.java:55) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.invocation.ContextClassLoaderInterceptor.processInvocation(ContextClassLoaderInterceptor.java:64)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.invocation.InterceptorContext.run(InterceptorContext.java:326)
at org.wildfly.security.manager.WildFlySecurityManager.doChecked(WildFlySecurityManager.java:448)
at org.jboss.invocation.AccessCheckingInterceptor.processInvocation(AccessCheckingInterceptor.java:61)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.invocation.InterceptorContext.run(InterceptorContext.java:326)
at org.jboss.invocation.PrivilegedWithCombinerInterceptor.processInvocation(PrivilegedWithCombinerInterceptor.java:80)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
at org.jboss.as.ee.component.ViewService$View.invoke(ViewService.java:185)
at org.jboss.as.ee.component.ViewDescription$1.processInvocation(ViewDescription.java:182)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ejb3.component.interceptors.LogDiagnosticContextRecoveryInterceptor.processInvocation(LogDiagnosticContextRecoveryInterceptor.java:79) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ejb3.component.interceptors.AsyncFutureInterceptorFactory$1$2.runInvocation(AsyncFutureInterceptorFactory.java:97) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.as.ejb3.component.interceptors.AsyncInvocationTask.run(AsyncInvocationTask.java:73) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) [rt.jar:1.7.0_10]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) [rt.jar:1.7.0_10]
at java.lang.Thread.run(Thread.java:722) [rt.jar:1.7.0_10]
at org.jboss.threads.JBossThread.run(JBossThread.java:122)
Caused by: javax.persistence.PersistenceException: org.hibernate.exception.ConstraintViolationException: could not execute statement
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1763) [hibernate-entitymanager-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1677) [hibernate-entitymanager-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1683) [hibernate-entitymanager-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.flush(AbstractEntityManagerImpl.java:1338) [hibernate-entitymanager-4.3.7.Final.jar:4.3.7.Final]
at org.jboss.as.jpa.container.AbstractEntityManager.flush(AbstractEntityManager.java:457) [wildfly-jpa-8.2.1.Final.jar:8.2.1.Final]
at sun.reflect.GeneratedMethodAccessor314.invoke(Unknown Source) [:1.7.0_10]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.7.0_10]
at java.lang.reflect.Method.invoke(Method.java:601) [rt.jar:1.7.0_10]
at org.jboss.weld.util.reflection.Reflections.invokeAndUnwrap(Reflections.java:414) [weld-core-impl-2.2.6.Final.jar:2014-10-03 10:05]
at org.jboss.weld.bean.builtin.CallableMethodHandler.invoke(CallableMethodHandler.java:42) [weld-core-impl-2.2.6.Final.jar:2014-10-03 10:05]
at org.jboss.weld.bean.proxy.EnterpriseTargetBeanInstance.invoke(EnterpriseTargetBeanInstance.java:56) [weld-core-impl-2.2.6.Final.jar:2014-10-03 10:05]
at org.jboss.weld.bean.proxy.ProxyMethodHandler.invoke(ProxyMethodHandler.java:100) [weld-core-impl-2.2.6.Final.jar:2014-10-03 10:05]
at org.jboss.weldx.persistence.EntityManager$1916316266$Proxy$_$$_Weld$Proxy$.flush(Unknown Source) [hibernate-jpa-2.1-api-1.0.0.Final.jar:]
at org.jboss.aerogear.unifiedpush.jpa.dao.impl.JPABaseDao.update(JPABaseDao.java:75) [unifiedpush-model-jpa-1.1.3.Final.jar:1.1.3.Final]
at org.jboss.aerogear.unifiedpush.service.impl.ClientInstallationServiceImpl.updateInstallation(ClientInstallationServiceImpl.java:139) [unifiedpush-service-1.1.3.Final.jar:1.1.3.Final]
at org.jboss.aerogear.unifiedpush.service.impl.ClientInstallationServiceImpl.updateInstallation(ClientInstallationServiceImpl.java:157) [unifiedpush-service-1.1.3.Final.jar:1.1.3.Final]
at org.jboss.aerogear.unifiedpush.service.impl.ClientInstallationServiceImpl.addInstallation(ClientInstallationServiceImpl.java:79) [unifiedpush-service-1.1.3.Final.jar:1.1.3.Final]
at sun.reflect.GeneratedMethodAccessor302.invoke(Unknown Source) [:1.7.0_10]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.7.0_10]
at java.lang.reflect.Method.invoke(Method.java:601) [rt.jar:1.7.0_10]
at org.jboss.as.ee.component.ManagedReferenceMethodInterceptor.processInvocation(ManagedReferenceMethodInterceptor.java:52)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.invocation.WeavedInterceptor.processInvocation(WeavedInterceptor.java:53)
at org.jboss.as.ee.component.interceptors.UserInterceptorFactory$1.processInvocation(UserInterceptorFactory.java:63)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.invocation.InterceptorContext$Invocation.proceed(InterceptorContext.java:407)
at org.jboss.as.weld.ejb.Jsr299BindingsInterceptor.doMethodInterception(Jsr299BindingsInterceptor.java:82) [wildfly-weld-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.as.weld.ejb.Jsr299BindingsInterceptor.processInvocation(Jsr299BindingsInterceptor.java:93) [wildfly-weld-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.as.ee.component.interceptors.UserInterceptorFactory$1.processInvocation(UserInterceptorFactory.java:63)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.invocation.WeavedInterceptor.processInvocation(WeavedInterceptor.java:53)
at org.jboss.as.ee.component.interceptors.UserInterceptorFactory$1.processInvocation(UserInterceptorFactory.java:63)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ejb3.component.invocationmetrics.ExecutionTimeInterceptor.processInvocation(ExecutionTimeInterceptor.java:43) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.jpa.interceptor.SBInvocationInterceptor.processInvocation(SBInvocationInterceptor.java:47) [wildfly-jpa-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.invocation.InterceptorContext$Invocation.proceed(InterceptorContext.java:407)
at org.jboss.weld.ejb.AbstractEJBRequestScopeActivationInterceptor.aroundInvoke(AbstractEJBRequestScopeActivationInterceptor.java:55) [weld-core-impl-2.2.6.Final.jar:2014-10-03 10:05]
at org.jboss.as.weld.ejb.EjbRequestScopeActivationInterceptor.processInvocation(EjbRequestScopeActivationInterceptor.java:83) [wildfly-weld-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ee.concurrent.ConcurrentContextInterceptor.processInvocation(ConcurrentContextInterceptor.java:45) [wildfly-ee-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.invocation.InitialInterceptor.processInvocation(InitialInterceptor.java:21)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.invocation.ChainedInterceptor.processInvocation(ChainedInterceptor.java:61)
at org.jboss.as.ee.component.interceptors.ComponentDispatcherInterceptor.processInvocation(ComponentDispatcherInterceptor.java:53)
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ejb3.component.interceptors.NonPooledEJBComponentInstanceAssociatingInterceptor.processInvocation(NonPooledEJBComponentInstanceAssociatingInterceptor.java:59) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
at org.jboss.invocation.InterceptorContext.proceed(InterceptorContext.java:309)
at org.jboss.as.ejb3.tx.CMTTxInterceptor.invokeInOurTx(CMTTxInterceptor.java:273) [wildfly-ejb3-8.2.1.Final.jar:8.2.1.Final]
... 38 more
Caused by: org.hibernate.exception.ConstraintViolationException: could not execute statement
at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:129) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:211) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:62) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.persister.collection.AbstractCollectionPersister.recreate(AbstractCollectionPersister.java:1311) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.action.internal.CollectionRecreateAction.execute(CollectionRecreateAction.java:67) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:463) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:349) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:350) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:56) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1222) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.flush(AbstractEntityManagerImpl.java:1335) [hibernate-entitymanager-4.3.7.Final.jar:4.3.7.Final]
... 85 more
Caused by: org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "installation_category_pkey"
Detail: Key (installation_id, category_id)=(78bf2331-2ce6-400b-a4cd-7a770c9598c5, 55) already exists.
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2157)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1886)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:255)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:559)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:417)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:363)
at org.jboss.jca.adapters.jdbc.WrappedPreparedStatement.executeUpdate(WrappedPreparedStatement.java:493)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:208) [hibernate-core-4.3.7.Final.jar:4.3.7.Final]
... 94 more