Jenkins details:Jenkins ver. 1.631

Keep getting the following exception on restart:

hudson.util.HudsonFailedToLoad: org.jvnet.hudson.reactor.ReactorException: java.lang.VerifyError: Expecting a stackmap frame at branch target 29
Exception Details:
Location:
hudson/plugins/emailext/watching/EmailExtWatchAction$UserProperty.<init>(Ljava/util/List;)V @17: ifeq
Reason:
Expected stackmap frame at this location.
Bytecode:
0x0000000: 2ab7 0013 2abb 0015 59b7 0016 1202 b800
0x0000010: 1a99 000c c000 1cb5 001f a700 06b5 0021
0x0000020: 2bc6 001c 2a2b b800 2712 02b8 001a 9900
0x0000030: 0cc0 001c b500 1fa7 0006 b500 21b1

at hudson.WebAppMain$3.run(WebAppMain.java:237)
Caused by: org.jvnet.hudson.reactor.ReactorException: java.lang.VerifyError: Expecting a stackmap frame at branch target 29
Exception Details:
Location:
hudson/plugins/emailext/watching/EmailExtWatchAction$UserProperty.<init>(Ljava/util/List;)V @17: ifeq
Reason:
Expected stackmap frame at this location.
Bytecode:
0x0000000: 2ab7 0013 2abb 0015 59b7 0016 1202 b800
0x0000010: 1a99 000c c000 1cb5 001f a700 06b5 0021
0x0000020: 2bc6 001c 2a2b b800 2712 02b8 001a 9900
0x0000030: 0cc0 001c b500 1fa7 0006 b500 21b1

at org.jvnet.hudson.reactor.Reactor.execute(Reactor.java:269)
at jenkins.InitReactorRunner.run(InitReactorRunner.java:44)
at jenkins.model.Jenkins.executeReactor(Jenkins.java:910)
at jenkins.model.Jenkins.<init>(Jenkins.java:818)
at hudson.model.Hudson.<init>(Hudson.java:85)
at hudson.model.Hudson.<init>(Hudson.java:81)
at hudson.WebAppMain$3.run(WebAppMain.java:225)
Caused by: java.lang.VerifyError: Expecting a stackmap frame at branch target 29
Exception Details:
Location:
hudson/plugins/emailext/watching/EmailExtWatchAction$UserProperty.<init>(Ljava/util/List;)V @17: ifeq
Reason:
Expected stackmap frame at this location.
Bytecode:
0x0000000: 2ab7 0013 2abb 0015 59b7 0016 1202 b800
0x0000010: 1a99 000c c000 1cb5 001f a700 06b5 0021
0x0000020: 2bc6 001c 2a2b b800 2712 02b8 001a 9900
0x0000030: 0cc0 001c b500 1fa7 0006 b500 21b1

at hudson.plugins.emailext.watching.EmailExtWatchAction$UserProperty$DescriptorImpl.newInstance(EmailExtWatchAction.java:61)
at hudson.plugins.emailext.watching.EmailExtWatchAction$UserProperty$DescriptorImpl.newInstance(EmailExtWatchAction.java:48)
at hudson.model.User.load(User.java:192)
at hudson.model.User.<init>(User.java:141)
at hudson.model.User.getOrCreate(User.java:452)
at hudson.model.User.get(User.java:506)
at hudson.model.User.current(User.java:490)
at hudson.plugins.jobConfigHistory.PluginUtils.getHistoryDao(PluginUtils.java:81)
at hudson.plugins.jobConfigHistory.PluginUtils.getHistoryDao(PluginUtils.java:62)
at hudson.plugins.jobConfigHistory.ComputerHistoryListener.onChange(ComputerHistoryListener.java:92)
at hudson.plugins.jobConfigHistory.ComputerHistoryListener.onConfigurationChange(ComputerHistoryListener.java:52)
at hudson.model.AbstractCIBase.updateComputerList(AbstractCIBase.java:209)
at jenkins.model.Jenkins.updateComputerList(Jenkins.java:1233)
at jenkins.model.Nodes$6.run(Nodes.java:254)
at hudson.model.Queue._withLock(Queue.java:1286)
at hudson.model.Queue.withLock(Queue.java:1169)
at jenkins.model.Nodes.load(Nodes.java:245)
at jenkins.model.Jenkins$16.run(Jenkins.java:2671)
at org.jvnet.hudson.reactor.TaskGraphBuilder$TaskImpl.run(TaskGraphBuilder.java:169)
at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:282)
at jenkins.model.Jenkins$7.runTask(Jenkins.java:899)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:210)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:117)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

Only way to avoid this is disable/uninstall email-ext plugin.