Stacktrace is below. Will include job configuration if you need it.
This error occurrs when the first multijob phase build step is ran, which comes after two regular build steps.

ERROR: Build step failed with exception
java.lang.NullPointerException
at com.tikal.jenkins.plugins.multijob.MultiJobBuilder.getScmChange(MultiJobBuilder.java:171)
at com.tikal.jenkins.plugins.multijob.MultiJobBuilder.perform(MultiJobBuilder.java:243)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:785)
at hudson.model.Build$BuildExecution.build(Build.java:205)
at hudson.model.Build$BuildExecution.doRun(Build.java:162)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:537)
at com.tikal.jenkins.plugins.multijob.MultiJobBuild$MultiJobRunnerImpl.run(MultiJobBuild.java:136)
at hudson.model.Run.execute(Run.java:1741)
at com.tikal.jenkins.plugins.multijob.MultiJobBuild.run(MultiJobBuild.java:73)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:408)
Build step 'MultiJob Phase' marked build as failure