All builds suddenly failing before they start

TeamCity reports this error on all build configurations that try to start now.  Any idea why?  Could this possibly be a low memory condition?

Patch is broken, can be found in file: C:\BuildAgents\BuildAgent1\temp\cache\temp7189519047806849983patch_1496
[13:40:39]: Unhandled error occurred, patch construction failed: jetbrains/buildServer/serverSide/systemProblems/SystemProblemNotificationEngine$BuiltTypeVcsRootPair jetbrains.buildServer.agent.impl.patch.PatchDownloaderImpl$1: Server was not able to build correct patch, most likely due to VCS errors, will try again.      at jetbrains.buildServer.agent.impl.patch.PatchDownloaderImpl.throwError(PatchDownloaderImpl.java:113)      at jetbrains.buildServer.agent.impl.patch.PatchDownloaderImpl.checkPatch(PatchDownloaderImpl.java:103)      at jetbrains.buildServer.agent.impl.patch.PatchDownloaderImpl.copyPatchAndCheck(PatchDownloaderImpl.java:64)      at jetbrains.buildServer.agent.impl.patch.UpdateSourcesPatcherBase.copyPatchToTempFile(UpdateSourcesPatcherBase.java:70)      at jetbrains.buildServer.agent.impl.patch.UpdateSourcesFromServer.updateSources(UpdateSourcesFromServer.java:62)      at jetbrains.buildServer.agent.impl.patch.UpdateSourcesBuildStageBase.doSourceUpdate(UpdateSourcesBuildStageBase.java:90)      at jetbrains.buildServer.agent.impl.patch.UpdateSourcesBuildStageBase.doRecoverableStage(UpdateSourcesBuildStageBase.java:58)      at jetbrains.buildServer.agent.impl.buildStages.startStages.RecoverableBuildStage.doLastAttempt(RecoverableBuildStage.java:112)      at jetbrains.buildServer.agent.impl.buildStages.startStages.RecoverableBuildStage.doBuildStage(RecoverableBuildStage.java:70)      at jetbrains.buildServer.agent.impl.buildStages.BuildStagesExecutor$1.callStage(BuildStagesExecutor.java:31)      at jetbrains.buildServer.agent.impl.buildStages.BuildStagesExecutor$1.callStage(BuildStagesExecutor.java:29)      at jetbrains.buildServer.agent.impl.buildStages.StagesExecutor.callRunStage(StagesExecutor.java:68)      at jetbrains.buildServer.agent.impl.buildStages.StagesExecutor.doStages(StagesExecutor.java:31)      at jetbrains.buildServer.agent.impl.buildStages.BuildStagesExecutor.doStages(BuildStagesExecutor.java:24)      at jetbrains.buildServer.agent.impl.BuildRunAction.doStages(BuildRunAction.java:65)      at jetbrains.buildServer.agent.impl.BuildRunAction.runBuild(BuildRunAction.java:48)      at jetbrains.buildServer.agent.impl.BuildAgentImpl.doActualBuild(BuildAgentImpl.java:250)      at jetbrains.buildServer.agent.impl.BuildAgentImpl.access$100(BuildAgentImpl.java:48)      at jetbrains.buildServer.agent.impl.BuildAgentImpl$1.run(BuildAgentImpl.java:223)      at java.lang.Thread.run(Unknown Source) Caused by: jetbrains.buildServer.vcs.patches.UnsuccessfulPatchException: Unhandled error occurred, patch construction failed: jetbrains/buildServer/serverSide/systemProblems/SystemProblemNotificationEngine$BuiltTypeVcsRootPair      at jetbrains.buildServer.vcs.patches.AbstractPatcher$1.fail(AbstractPatcher.java:93)      at jetbrains.buildServer.vcs.patches.LowLevelPatcher.readPatchStream(LowLevelPatcher.java:156)      at jetbrains.buildServer.vcs.patches.LowLevelPatcher.applyPatch(LowLevelPatcher.java:79)      at jetbrains.buildServer.vcs.patches.AbstractPatcher.applyPatch(AbstractPatcher.java:42)      at jetbrains.buildServer.agent.impl.patch.PatchApplierImpl.applyPatch(PatchApplierImpl.java:18)      at jetbrains.buildServer.agent.impl.patch.PatchDownloaderImpl.checkPatchInFileIsCompleted(PatchDownloaderImpl.java:83)      at jetbrains.buildServer.agent.impl.patch.PatchDownloaderImpl.checkPatch(PatchDownloaderImpl.java:93)      ... 18 more