Running on Tomcat 5.5.20, with versions 1.225 and 1.226, trying to submit a
change to a project results in :

javax.servlet.ServletException
org.kohsuke.stapler.Stapler.invoke(Stapler.java:449)
org.kohsuke.stapler.MetaClass$9.doDispatch(MetaClass.java:254)
org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30)
org.kohsuke.stapler.Stapler.invoke(Stapler.java:440)
org.kohsuke.stapler.Stapler.invoke(Stapler.java:361)
org.kohsuke.stapler.Stapler.service(Stapler.java:121)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:38)
hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:30)
hudson.security.HudsonFilter.doFilter(HudsonFilter.java:88)

root cause

java.lang.NullPointerException
org.kohsuke.stapler.RequestImpl.bindJSON(RequestImpl.java:305)
hudson.model.Descriptor.newInstance(Descriptor.java:136)
hudson.scm.RepositoryBrowsers.createInstance(RepositoryBrowsers.java:51)
hudson.scm.SubversionSCM$DescriptorImpl.newInstance(SubversionSCM.java:1020)
hudson.scm.SubversionSCM$DescriptorImpl.newInstance(SubversionSCM.java:799)
hudson.model.Descriptor.newInstance(Descriptor.java:133)
hudson.scm.SCMS.parseSCM(SCMS.java:37)
hudson.model.AbstractProject.submit(AbstractProject.java:902)
hudson.model.Project.submit(Project.java:144)
hudson.model.FreeStyleProject.submit(FreeStyleProject.java:68)
hudson.model.Job.doConfigSubmit(Job.java:826)
hudson.model.AbstractProject.doConfigSubmit(AbstractProject.java:301)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:597)
org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:103)
org.kohsuke.stapler.Function.bindAndinvoke(Function.java:57)
org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:75)
org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30)
org.kohsuke.stapler.Stapler.invoke(Stapler.java:440)
org.kohsuke.stapler.MetaClass$9.doDispatch(MetaClass.java:254)
org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30)
org.kohsuke.stapler.Stapler.invoke(Stapler.java:440)
org.kohsuke.stapler.Stapler.invoke(Stapler.java:361)
org.kohsuke.stapler.Stapler.service(Stapler.java:121)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:38)
hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:30)
hudson.security.HudsonFilter.doFilter(HudsonFilter.java:88)