Updated from Timestamper version 1.11.3 to 1.11.4, restarted Jenkins.  Now will not start, Jenkins logs shows following.  Have to remove my jenkins.yaml to get it to start.

2020-07-27 18:24:51.888+0000 [id=26] SEVERE jenkins.InitReactorRunner$1#onTaskFailed: Failed ConfigurationAsCode.init
io.jenkins.plugins.casc.ConfiguratorException: Invalid configuration elements for type class jenkins.model.GlobalConfigurationCategory$Unclassified : timestamperConfig.
Available attributes : administrativeMonitorsConfiguration, ansiColorBuildWrapper, artifactManager, buildDiscarders, buildStepOperation, casCGlobalConfig, codeBuilder, defaultFolderConfiguration, defaultView, extendedEmailPublisher, extensibleChoiceParameterDefinition, gitLabConnectionConfig, gitParameter, gitSCM, globalDefaultFlowDurabilityLevel, globalLibraries, httpRequestGlobalConfig, location, lockableResourcesManager, mailer, masterBuild, mavenModuleSet, metricsAccessKey, myView, nodeProperties, pipeline-model-docker, plugin, pollSCM, projectNamingStrategy, quietPeriod, rebuildDescriptor, resourceRoot, s3Upload, sSHBuildWrapper, scmRetryCount, shell, singleConditionalBuilder, slackNotifier, throttleJobProperty, upstream, usageStatistics, viewsTabBar, whitelist
at io.jenkins.plugins.casc.BaseConfigurator.handleUnknown(BaseConfigurator.java:376)
at io.jenkins.plugins.casc.BaseConfigurator.configure(BaseConfigurator.java:365)
at io.jenkins.plugins.casc.BaseConfigurator.check(BaseConfigurator.java:287)
at io.jenkins.plugins.casc.ConfigurationAsCode.lambda$checkWith$8(ConfigurationAsCode.java:755)
at io.jenkins.plugins.casc.ConfigurationAsCode.invokeWith(ConfigurationAsCode.java:691)
Caused: io.jenkins.plugins.casc.ConfiguratorException: unclassified: error configuring 'unclassified' with class io.jenkins.plugins.casc.impl.configurators.GlobalConfigurationCategoryConfigurator configurator
at io.jenkins.plugins.casc.ConfigurationAsCode.invokeWith(ConfigurationAsCode.java:697)
at io.jenkins.plugins.casc.ConfigurationAsCode.checkWith(ConfigurationAsCode.java:755)
at io.jenkins.plugins.casc.ConfigurationAsCode.configureWith(ConfigurationAsCode.java:740)
at io.jenkins.plugins.casc.ConfigurationAsCode.configureWith(ConfigurationAsCode.java:616)
at io.jenkins.plugins.casc.ConfigurationAsCode.configure(ConfigurationAsCode.java:298)
at io.jenkins.plugins.casc.ConfigurationAsCode.init(ConfigurationAsCode.java:290)
Caused: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:104)
Caused: java.lang.Error
at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:110)
at hudson.init.TaskMethodFinder$TaskImpl.run(TaskMethodFinder.java:175)
at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:296)
at jenkins.model.Jenkins$5.runTask(Jenkins.java:1131)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:214)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:117)
at jenkins.security.ImpersonatingExecutorService$1.run(ImpersonatingExecutorService.java:59)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
2020-07-27 18:24:51.890+0000 [id=20] SEVERE hudson.util.BootFailure#publish: Failed to initialize Jenkins
io.jenkins.plugins.casc.ConfiguratorException: Invalid configuration elements for type class jenkins.model.GlobalConfigurationCategory$Unclassified : timestamperConfig.
Available attributes : administrativeMonitorsConfiguration, ansiColorBuildWrapper, artifactManager, buildDiscarders, buildStepOperation, casCGlobalConfig, codeBuilder, defaultFolderConfiguration, defaultView, extendedEmailPublisher, extensibleChoiceParameterDefinition, gitLabConnectionConfig, gitParameter, gitSCM, globalDefaultFlowDurabilityLevel, globalLibraries, httpRequestGlobalConfig, location, lockableResourcesManager, mailer, masterBuild, mavenModuleSet, metricsAccessKey, myView, nodeProperties, pipeline-model-docker, plugin, pollSCM, projectNamingStrategy, quietPeriod, rebuildDescriptor, resourceRoot, s3Upload, sSHBuildWrapper, scmRetryCount, shell, singleConditionalBuilder, slackNotifier, throttleJobProperty, upstream, usageStatistics, viewsTabBar, whitelist
at io.jenkins.plugins.casc.BaseConfigurator.handleUnknown(BaseConfigurator.java:376)
at io.jenkins.plugins.casc.BaseConfigurator.configure(BaseConfigurator.java:365)
at io.jenkins.plugins.casc.BaseConfigurator.check(BaseConfigurator.java:287)
at io.jenkins.plugins.casc.ConfigurationAsCode.lambda$checkWith$8(ConfigurationAsCode.java:755)
at io.jenkins.plugins.casc.ConfigurationAsCode.invokeWith(ConfigurationAsCode.java:691)
Caused: io.jenkins.plugins.casc.ConfiguratorException: unclassified: error configuring 'unclassified' with class io.jenkins.plugins.casc.impl.configurators.GlobalConfigurationCategoryConfigurator configurator
at io.jenkins.plugins.casc.ConfigurationAsCode.invokeWith(ConfigurationAsCode.java:697)
at io.jenkins.plugins.casc.ConfigurationAsCode.checkWith(ConfigurationAsCode.java:755)
at io.jenkins.plugins.casc.ConfigurationAsCode.configureWith(ConfigurationAsCode.java:740)
at io.jenkins.plugins.casc.ConfigurationAsCode.configureWith(ConfigurationAsCode.java:616)
at io.jenkins.plugins.casc.ConfigurationAsCode.configure(ConfigurationAsCode.java:298)
at io.jenkins.plugins.casc.ConfigurationAsCode.init(ConfigurationAsCode.java:290)
Caused: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:104)
Caused: java.lang.Error
at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:110)
at hudson.init.TaskMethodFinder$TaskImpl.run(TaskMethodFinder.java:175)
at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:296)
at jenkins.model.Jenkins$5.runTask(Jenkins.java:1131)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:214)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:117)
at jenkins.security.ImpersonatingExecutorService$1.run(ImpersonatingExecutorService.java:59)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused: org.jvnet.hudson.reactor.ReactorException
at org.jvnet.hudson.reactor.Reactor.execute(Reactor.java:282)
at jenkins.InitReactorRunner.run(InitReactorRunner.java:50)
at jenkins.model.Jenkins.executeReactor(Jenkins.java:1164)
at jenkins.model.Jenkins.<init>(Jenkins.java:964)
at hudson.model.Hudson.<init>(Hudson.java:85)
at hudson.model.Hudson.<init>(Hudson.java:81)
at hudson.WebAppMain$3.run(WebAppMain.java:262)
Caused: hudson.util.HudsonFailedToLoad
at hudson.WebAppMain$3.run(WebAppMain.java:279)
2020-07-27 18:24:51.902+0000 [id=20] INFO jenkins.model.Jenkins#cleanUp: Stopping Jenkins
2020-07-27 18:24:51.953+0000 [id=20] INFO jenkins.model.Jenkins$18#onAttained: Started termination
2020-07-27 18:24:51.968+0000 [id=20] INFO jenkins.model.Jenkins$18#onAttained: Completed termination
2020-07-27 18:24:51.968+0000 [id=20] INFO jenkins.model.Jenkins#_cleanUpDisconnectComputers: Starting node disconnection
2020-07-27 18:24:51.971+0000 [id=20] INFO jenkins.model.Jenkins#_cleanUpShutdownPluginManager: Stopping plugin manager
2020-07-27 18:24:52.559+0000 [id=20] INFO jenkins.model.Jenkins#_cleanUpPersistQueue: Persisting build queue
2020-07-27 18:24:52.586+0000 [id=20] INFO jenkins.model.Jenkins#_cleanUpAwaitDisconnects: Waiting for node disconnection completion
2020-07-27 18:24:52.586+0000 [id=20] INFO jenkins.model.Jenkins#cleanUp: Jenkins stopped