After upgrading from 2.25 to 2.30.2 on Jenkins 1.480.3, every matrix project throws the following exception at the end of the matrix parent job.

I have the "Trigger only for parent job" option enabled.

FATAL: hudson.model.AbstractBuild.getPreviousBuild()Lhudson/model/AbstractBuild;
java.lang.NoSuchMethodError: hudson.model.AbstractBuild.getPreviousBuild()Lhudson/model/AbstractBuild;
at hudson.plugins.emailext.plugins.trigger.FixedTrigger.trigger(FixedTrigger.java:21)
at hudson.plugins.emailext.ExtendedEmailPublisher._perform(ExtendedEmailPublisher.java:282)
at hudson.plugins.emailext.ExtendedEmailPublisher.access$100(ExtendedEmailPublisher.java:82)
at hudson.plugins.emailext.ExtendedEmailPublisher$1.endBuild(ExtendedEmailPublisher.java:800)
at hudson.matrix.MatrixBuild$MatrixBuildExecution.post2(MatrixBuild.java:387)
at hudson.model.AbstractBuild$AbstractBuildExecution.post(AbstractBuild.java:640)
at hudson.model.Run.execute(Run.java:1527)
at hudson.matrix.MatrixBuild.run(MatrixBuild.java:289)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:237)
at hudson.model.OneOffExecutor.run(OneOffExecutor.java:66)