Any MSBuild (3.5 and 4.0) reported warnings cause projects to have the following violations at completion of build:

ERROR: Publisher hudson.plugins.warnings.WarningsPublisher aborted due to exception
java.io.IOException: Error: No warning parsers defined.
at hudson.plugins.warnings.WarningsPublisher.perform(WarningsPublisher.java:229)
at hudson.plugins.analysis.core.HealthAwarePublisher.perform(HealthAwarePublisher.java:310)
at hudson.tasks.BuildStepMonitor$2.perform(BuildStepMonitor.java:27)
at hudson.model.AbstractBuild$AbstractRunner.perform(AbstractBuild.java:682)
at hudson.model.AbstractBuild$AbstractRunner.performAllBuildSteps(AbstractBuild.java:657)
at hudson.model.AbstractBuild$AbstractRunner.performAllBuildSteps(AbstractBuild.java:635)
at hudson.model.Build$RunnerImpl.post2(Build.java:161)
at hudson.model.AbstractBuild$AbstractRunner.post(AbstractBuild.java:604)
at hudson.model.Run.run(Run.java:1400)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:175)

All builds with MSBuild.exe build warnings are failing due to this "missing parser" issue. Do not understand why MSBuild support suddenly not working anymore as it is part of the list of automatically supported items accroding to the https://wiki.jenkins-ci.org/display/JENKINS/Warnings+Plugin post.

Thinking it was an issue with the slave.jar as others point out, I then manually moved the latest slave.jar file to all the used slaves, restarted the windows services running them, and resarted the service that the master is running under, and while I see new files are out there on the slaves I sill get the parser error running the slave.jar compiled on 7/20/2011.

Have removed the warnings plug-in and am able to run without it, but want it back and need to figure out why it is failing.