If a process contains a Multi Instance DMN Business Rule Task which has enabled the property Multi Instance Async After a exception is throw that the transient DMN result variable decisionResult cannot be updated.
org.camunda.bpm.engine.ProcessEngineException: ENGINE-03064 The variable with name 'decisionResult' can not be updated because it is transient and read-only. at org.camunda.bpm.engine.impl.db.EnginePersistenceLogger.updateTransientVariableException(EnginePersistenceLogger.java:526) at org.camunda.bpm.engine.impl.persistence.entity.VariableInstanceEntity.setValue(VariableInstanceEntity.java:263) at org.camunda.bpm.engine.impl.core.variable.scope.AbstractVariableScope.setVariableLocal(AbstractVariableScope.java:312) at org.camunda.bpm.engine.impl.core.variable.scope.AbstractVariableScope.setVariableLocal(AbstractVariableScope.java:357) at org.camunda.bpm.engine.impl.persistence.entity.VariableInstanceEntity.onImplicitValueUpdate(VariableInstanceEntity.java:552) at org.camunda.bpm.engine.impl.persistence.entity.util.TypedValueField.onCommandContextClose(TypedValueField.java:167) at org.camunda.bpm.engine.impl.interceptor.CommandContext.fireCommandContextClose(CommandContext.java:304) at org.camunda.bpm.engine.impl.interceptor.CommandContext.close(CommandContext.java:248) at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:113) at org.camunda.bpm.engine.impl.interceptor.ProcessApplicationContextInterceptor.execute(ProcessApplicationContextInterceptor.java:66) at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:30) at org.camunda.bpm.engine.impl.ProcessInstantiationBuilderImpl.execute(ProcessInstantiationBuilderImpl.java:145) at org.camunda.bpm.engine.impl.ProcessInstantiationBuilderImpl.execute(ProcessInstantiationBuilderImpl.java:117) at org.camunda.bpm.engine.impl.RuntimeServiceImpl.startProcessInstanceByKey(RuntimeServiceImpl.java:85) at org.camunda.bpm.unittest.SimpleTestCase.shouldExecuteProcess(SimpleTestCase.java:46) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.rules.TestWatcher$1.evaluate(TestWatcher.java:55) at org.camunda.bpm.engine.test.ProcessEngineRule$1.evaluate(ProcessEngineRule.java:165) at org.junit.rules.RunRules.evaluate(RunRules.java:20)