Email-ext plugin is not sending mail is the build is failed but there is no change in the source code.

Hi,

Email-ext plugin is not sending mail is the build is failed but there is no change in the source code. Build might be failed for environmental issues. I get following exception in Jenkins log

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2472 SEVERE: Executor threw an exception
2473 java.lang.NoClassDefFoundError: org/sonatype/aether/util/StringUtils
2474 at hudson.plugins.emailext.plugins.content.ChangesSinceLastBuildContent.evaluate(ChangesSinceLastBuildContent.java:56)
2475 at org.jenkinsci.plugins.tokenmacro.DataBoundTokenMacro.evaluate(DataBoundTokenMacro.java:177)
2476 at org.jenkinsci.plugins.tokenmacro.TokenMacro.expand(TokenMacro.java:182)
2477 at org.jenkinsci.plugins.tokenmacro.TokenMacro.expandAll(TokenMacro.java:233)
2478 at hudson.plugins.emailext.plugins.ContentBuilder.transformText(ContentBuilder.java:63)
2479 at hudson.plugins.emailext.ExtendedEmailPublisher.getContent(ExtendedEmailPublisher.java:705)
2480 at hudson.plugins.emailext.ExtendedEmailPublisher.createMail(ExtendedEmailPublisher.java:488)
2481 at hudson.plugins.emailext.ExtendedEmailPublisher.sendMail(ExtendedEmailPublisher.java:319)
2482 at hudson.plugins.emailext.ExtendedEmailPublisher._perform(ExtendedEmailPublisher.java:311)
2483 at hudson.plugins.emailext.ExtendedEmailPublisher.perform(ExtendedEmailPublisher.java:271)
2484 at hudson.tasks.BuildStepMonitor$3.perform(BuildStepMonitor.java:36)
2485 at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:804)
2486 at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:776)
2487 at hudson.model.Build$BuildExecution.cleanUp(Build.java:192)
2488 at hudson.model.Run.execute(Run.java:1642)
2489 at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
2490 at hudson.model.ResourceController.execute(ResourceController.java:88)
2491 at hudson.model.Executor.run(Executor.java:247)
2492

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I expect mail to be sent irrespective of source code changes. We also have few jobs which is for testing they do not have source code management system.

Thanks,
Bakkiaraj M