Till yesterday my jenkins jobs are working fine. But today its giving me the following error. Please explain me the situation and help me to fix it. 
 
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Stack trace

org.apache.commons.jelly.JellyTagException: jar:file:/var/cache/jenkins/war/WEB-INF/lib/jenkins-core-2.108.jar!/lib/form/block.jelly:32:22: <d:invokeBody> hudson/matrix/MatrixProject at org.apache.commons.jelly.impl.TagScript.handleException(TagScript.java:745) at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:289) at org.kohsuke.stapler.jelly.ReallyStaticTagLibrary$1.run(ReallyStaticTagLibrary.java:99) at org.kohsuke.stapler.jelly.ReallyStaticTagLibrary$1.run(ReallyStaticTagLibrary.java:99) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.apache.commons.jelly.tags.core.CoreTagLibrary$2.run(CoreTagLibrary.java:105) at org.kohsuke.stapler.jelly.CallTagLibScript.run(CallTagLibScript.java:120) at org.kohsuke.stapler.jelly.CallTagLibScript$1.run(CallTagLibScript.java:99) at org.apache.commons.jelly.tags.define.InvokeBodyTag.doTag(InvokeBodyTag.java:91) at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.kohsuke.stapler.jelly.CallTagLibScript$1.run(CallTagLibScript.java:99) at org.apache.commons.jelly.tags.define.InvokeBodyTag.doTag(InvokeBodyTag.java:91) at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269) at org.apache.commons.jelly.TagSupport.invokeBody(TagSupport.java:161) at org.apache.commons.jelly.tags.core.WhenTag.doTag(WhenTag.java:46) at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.apache.commons.jelly.TagSupport.invokeBody(TagSupport.java:161) at org.apache.commons.jelly.tags.core.ChooseTag.doTag(ChooseTag.java:38) at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.apache.commons.jelly.tags.core.CoreTagLibrary$2.run(CoreTagLibrary.java:105) at org.kohsuke.stapler.jelly.CallTagLibScript.run(CallTagLibScript.java:120) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.apache.commons.jelly.tags.core.CoreTagLibrary$2.run(CoreTagLibrary.java:105) at org.kohsuke.stapler.jelly.CallTagLibScript.run(CallTagLibScript.java:120) at org.apache.commons.jelly.tags.core.CoreTagLibrary$2.run(CoreTagLibrary.java:105) at org.kohsuke.stapler.jelly.CallTagLibScript.run(CallTagLibScript.java:120) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.apache.commons.jelly.tags.core.CoreTagLibrary$2.run(CoreTagLibrary.java:105) at org.kohsuke.stapler.jelly.JellyViewScript.run(JellyViewScript.java:95) at org.kohsuke.stapler.jelly.IncludeTag.doTag(IncludeTag.java:147) at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.kohsuke.stapler.jelly.CallTagLibScript$1.run(CallTagLibScript.java:99) at org.apache.commons.jelly.tags.define.InvokeBodyTag.doTag(InvokeBodyTag.java:91) at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269) at org.kohsuke.stapler.jelly.ReallyStaticTagLibrary$1.run(ReallyStaticTagLibrary.java:99) at org.kohsuke.stapler.jelly.ReallyStaticTagLibrary$1.run(ReallyStaticTagLibrary.java:99) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.apache.commons.jelly.tags.core.CoreTagLibrary$2.run(CoreTagLibrary.java:105) at org.kohsuke.stapler.jelly.CallTagLibScript.run(CallTagLibScript.java:120) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.kohsuke.stapler.jelly.ReallyStaticTagLibrary$1.run(ReallyStaticTagLibrary.java:99) at org.kohsuke.stapler.jelly.ReallyStaticTagLibrary$1.run(ReallyStaticTagLibrary.java:99) at org.kohsuke.stapler.jelly.ReallyStaticTagLibrary$1.run(ReallyStaticTagLibrary.java:99) at org.kohsuke.stapler.jelly.CallTagLibScript$1.run(CallTagLibScript.java:99) at org.apache.commons.jelly.tags.define.InvokeBodyTag.doTag(InvokeBodyTag.java:91) at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.apache.commons.jelly.tags.core.CoreTagLibrary$1.run(CoreTagLibrary.java:98) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.apache.commons.jelly.tags.core.CoreTagLibrary$2.run(CoreTagLibrary.java:105) at org.kohsuke.stapler.jelly.CallTagLibScript.run(CallTagLibScript.java:120) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.kohsuke.stapler.jelly.CallTagLibScript$1.run(CallTagLibScript.java:99) at org.apache.commons.jelly.tags.define.InvokeBodyTag.doTag(InvokeBodyTag.java:91) at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.kohsuke.stapler.jelly.ReallyStaticTagLibrary$1.run(ReallyStaticTagLibrary.java:99) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.kohsuke.stapler.jelly.ReallyStaticTagLibrary$1.run(ReallyStaticTagLibrary.java:99) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.kohsuke.stapler.jelly.ReallyStaticTagLibrary$1.run(ReallyStaticTagLibrary.java:99) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.kohsuke.stapler.jelly.ReallyStaticTagLibrary$1.run(ReallyStaticTagLibrary.java:99) at org.apache.commons.jelly.impl.ScriptBlock.run(ScriptBlock.java:95) at org.apache.commons.jelly.tags.core.CoreTagLibrary$2.run(CoreTagLibrary.java:105) at org.kohsuke.stapler.jelly.CallTagLibScript.run(CallTagLibScript.java:120) at org.apache.commons.jelly.tags.core.CoreTagLibrary$2.run(CoreTagLibrary.java:105) at org.kohsuke.stapler.jelly.JellyViewScript.run(JellyViewScript.java:95) at org.kohsuke.stapler.jelly.DefaultScriptInvoker.invokeScript(DefaultScriptInvoker.java:63) at org.kohsuke.stapler.jelly.DefaultScriptInvoker.invokeScript(DefaultScriptInvoker.java:53) at org.kohsuke.stapler.jelly.JellyFacet$1.dispatch(JellyFacet.java:97) at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:715) at org.kohsuke.stapler.Stapler.invoke(Stapler.java:845) at org.kohsuke.stapler.MetaClass$5.doDispatch(MetaClass.java:248) at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:58) at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:715) at org.kohsuke.stapler.Stapler.invoke(Stapler.java:845) at org.kohsuke.stapler.Stapler.invoke(Stapler.java:649) at org.kohsuke.stapler.Stapler.service(Stapler.java:238) at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:841) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650) at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:154) at com.smartcodeltd.jenkinsci.plugin.assetbundler.filters.LessCSS.doFilter(LessCSS.java:47) at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:151) at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:157) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637) at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:64) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:84) at hudson.security.UnwrapSecurityExceptionFilter.doFilter(UnwrapSecurityExceptionFilter.java:51) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at jenkins.security.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:117) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.ui.rememberme.RememberMeProcessingFilter.doFilter(RememberMeProcessingFilter.java:142) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:271) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at jenkins.security.BasicHeaderProcessor.doFilter(BasicHeaderProcessor.java:93) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:249) at hudson.security.HttpSessionContextIntegrationFilter2.doFilter(HttpSessionContextIntegrationFilter2.java:67) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:90) at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:171) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637) at org.kohsuke.stapler.compression.CompressionFilter.doFilter(CompressionFilter.java:49) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637) at hudson.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:82) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637) at org.kohsuke.stapler.DiagnosticThreadNameFilter.doFilter(DiagnosticThreadNameFilter.java:30) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:533) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:524) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132) at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:190) at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1595) at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:188) at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1253) at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:168) at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473) at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1564) at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:166) at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1155) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132) at org.eclipse.jetty.server.Server.handle(Server.java:564) at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:317) at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251) at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:279) at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:110) at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:124) at org.eclipse.jetty.util.thread.Invocable.invokePreferred(Invocable.java:128) at org.eclipse.jetty.util.thread.Invocable$InvocableExecutor.invoke(Invocable.java:222) at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:294) at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:199) at winstone.BoundedExecutorService$1.run(BoundedExecutorService.java:77) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1160) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) at java.lang.Thread.run(Thread.java:785) Caused by: java.lang.NoClassDefFoundError: hudson/matrix/MatrixProject at hudson.plugins.plot.PlotDescriptor.isApplicable(PlotDescriptor.java:42) at hudson.tasks.BuildStepDescriptor.filter(BuildStepDescriptor.java:84) at hudson.Functions.getPublisherDescriptors(Functions.java:901) at sun.reflect.GeneratedMethodAccessor593.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55) at java.lang.reflect.Method.invoke(Method.java:508) at org.apache.commons.jexl.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:258) at org.apache.commons.jexl.parser.ASTMethod.execute(ASTMethod.java:104) at org.apache.commons.jexl.parser.ASTReference.execute(ASTReference.java:83) at org.apache.commons.jexl.parser.ASTReference.value(ASTReference.java:57) at org.apache.commons.jexl.parser.ASTReferenceExpression.value(ASTReferenceExpression.java:51) at org.apache.commons.jexl.ExpressionImpl.evaluate(ExpressionImpl.java:80) at hudson.ExpressionFactory2$JexlExpression.evaluate(ExpressionFactory2.java:74) at org.kohsuke.stapler.jelly.CallTagLibScript.run(CallTagLibScript.java:58) at org.kohsuke.stapler.jelly.CallTagLibScript$1.run(CallTagLibScript.java:99) at org.apache.commons.jelly.tags.define.InvokeBodyTag.doTag(InvokeBodyTag.java:91) at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:269) ... 145 more Caused: javax.servlet.ServletException at org.kohsuke.stapler.jelly.JellyFacet$1.dispatch(JellyFacet.java:105) at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:715) at org.kohsuke.stapler.Stapler.invoke(Stapler.java:845) at org.kohsuke.stapler.MetaClass$5.doDispatch(MetaClass.java:248) at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:58) at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:715) at org.kohsuke.stapler.Stapler.invoke(Stapler.java:845) at org.kohsuke.stapler.Stapler.invoke(Stapler.java:649) at org.kohsuke.stapler.Stapler.service(Stapler.java:238) at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:841) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1650) at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:154) at com.smartcodeltd.jenkinsci.plugin.assetbundler.filters.LessCSS.doFilter(LessCSS.java:47) at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:151) at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:157) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637) at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:64) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:84) at hudson.security.UnwrapSecurityExceptionFilter.doFilter(UnwrapSecurityExceptionFilter.java:51) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at jenkins.security.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:117) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.ui.rememberme.RememberMeProcessingFilter.doFilter(RememberMeProcessingFilter.java:142) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:271) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at jenkins.security.BasicHeaderProcessor.doFilter(BasicHeaderProcessor.java:93) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:249) at hudson.security.HttpSessionContextIntegrationFilter2.doFilter(HttpSessionContextIntegrationFilter2.java:67) at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87) at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:90) at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:171) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637) at org.kohsuke.stapler.compression.CompressionFilter.doFilter(CompressionFilter.java:49) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637) at hudson.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:82) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637) at org.kohsuke.stapler.DiagnosticThreadNameFilter.doFilter(DiagnosticThreadNameFilter.java:30) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1637) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:533) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:524) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132) at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:190) at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1595) at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:188) at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1253) at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:168) at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:473) at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1564) at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:166) at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1155) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132) at org.eclipse.jetty.server.Server.handle(Server.java:564) at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:317) at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251) at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:279) at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:110) at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:124) at org.eclipse.jetty.util.thread.Invocable.invokePreferred(Invocable.java:128) at org.eclipse.jetty.util.thread.Invocable$InvocableExecutor.invoke(Invocable.java:222) at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:294) at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:199) at winstone.BoundedExecutorService$1.run(BoundedExecutorService.java:77) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1160) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) at java.lang.Thread.run(Thread.java:785)