Jenkins does not even start anymore. It just displays the following stacktrace:

org.apache.commons.jelly.JellyTagException: jar:file:/home/hudson/.hudson/war/WEB-INF/lib/jenkins-core-1.413.jar!/lib/layout/layout.jelly:130:53: No resource was found for com.thalesgroup.hudson.plugins.scons.SConsBuilderScriptFile
at org.apache.commons.jelly.impl.TagScript.handleException(TagScript.java:709)
at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:282)
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:119)
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:63)
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.JellyClassTearOff.serveIndexJelly(JellyClassTearOff.java:72)
at org.kohsuke.stapler.jelly.JellyFacet.handleIndexRequest(JellyFacet.java:114)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:550)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:646)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:477)
at org.kohsuke.stapler.Stapler.service(Stapler.java:159)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:45)
at winstone.ServletConfiguration.execute(ServletConfiguration.java:249)
at winstone.RequestDispatcher.forward(RequestDispatcher.java:335)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:378)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:94)
at hudson.plugins.greenballs.GreenBallFilter.doFilter(GreenBallFilter.java:52)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:97)
at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:86)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:47)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:162)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at hudson.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:81)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at winstone.RequestDispatcher.forward(RequestDispatcher.java:333)
at winstone.RequestHandlerThread.processRequest(RequestHandlerThread.java:244)
at winstone.RequestHandlerThread.run(RequestHandlerThread.java:150)
at java.lang.Thread.run(Thread.java:662)
Caused by: java.util.MissingResourceException: No resource was found for com.thalesgroup.hudson.plugins.scons.SConsBuilderScriptFile
at org.jvnet.localizer.ResourceBundleHolder.get(ResourceBundleHolder.java:104)
at org.jvnet.localizer.ResourceBundleHolder.get(ResourceBundleHolder.java:102)
at org.jvnet.localizer.ResourceBundleHolder.get(ResourceBundleHolder.java:102)
at org.jvnet.localizer.ResourceBundleHolder.format(ResourceBundleHolder.java:139)
at com.thalesgroup.hudson.plugins.scons.SConsInstallation$DescriptorImpl.getDisplayName(SConsInstallation.java:93)
at hudson.ExtensionComponent.compareTo(ExtensionComponent.java:80)
at hudson.ExtensionComponent.compareTo(ExtensionComponent.java:36)
at java.util.Arrays.mergeSort(Arrays.java:1144)
at java.util.Arrays.mergeSort(Arrays.java:1156)
at java.util.Arrays.mergeSort(Arrays.java:1155)
at java.util.Arrays.mergeSort(Arrays.java:1156)
at java.util.Arrays.mergeSort(Arrays.java:1155)
at java.util.Arrays.mergeSort(Arrays.java:1156)
at java.util.Arrays.mergeSort(Arrays.java:1156)
at java.util.Arrays.sort(Arrays.java:1079)
at java.util.Collections.sort(Collections.java:117)
at hudson.ExtensionList.sort(ExtensionList.java:249)
at hudson.ExtensionList.ensureLoaded(ExtensionList.java:210)
at hudson.ExtensionList.getComponents(ExtensionList.java:126)
at hudson.DescriptorExtensionList.load(DescriptorExtensionList.java:163)
at hudson.ExtensionList.ensureLoaded(ExtensionList.java:208)
at hudson.ExtensionList.iterator(ExtensionList.java:115)
at org.apache.commons.jelly.expression.ExpressionSupport.evaluateAsIterator(ExpressionSupport.java:101)
at org.apache.commons.jelly.tags.core.ForEachTag.doTag(ForEachTag.java:89)
at org.apache.commons.jelly.impl.TagScript.run(TagScript.java:270)
... 41 more