Steps to reproduce:

1. Confluence 3.5.13
2. Installed, booted up
3. Postregres DB
4. Shutdown, applied patch following advisory
5. admin panel not accessible
6. content appears to be missing
7. see errors in the logs:

   2014-05-22 16:28:50,308 ERROR [http-8080-1] [[Standalone].[localhost].[/].[action]] log Servlet.service() for servlet action threw exception
    -- referer: http://localhost:8080/dashboard.action | url: /display/ds/Example+Human+Resources+Page | userName: admin
   java.lang.AbstractMethodError: com.atlassian.xwork10.Xwork10VersionSupport.extractMethod(Lcom/opensymphony/xwork/ActionInvocation;)Ljava/lang/reflect/Method;
   	at com.atlassian.xwork.interceptors.XsrfTokenInterceptor.intercept(XsrfTokenInterceptor.java:78)
   	at com.atlassian.confluence.xwork.ConfluenceXsrfTokenInterceptor.intercept(ConfluenceXsrfTokenInterceptor.java:25)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.atlassian.confluence.security.interceptors.CaptchaInterceptor.intercept(CaptchaInterceptor.java:46)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.atlassian.confluence.util.LoggingContextInterceptor.intercept(LoggingContextInterceptor.java:49)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.atlassian.confluence.core.CancellingInterceptor.intercept(CancellingInterceptor.java:23)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.atlassian.confluence.security.websudo.WebSudoInterceptor.intercept(WebSudoInterceptor.java:58)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.atlassian.confluence.security.actions.PermissionCheckInterceptor.intercept(PermissionCheckInterceptor.java:57)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.atlassian.confluence.setup.webwork.BootstrapAwareInterceptor.intercept(BootstrapAwareInterceptor.java:26)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.atlassian.confluence.user.actions.UserAwareInterceptor.intercept(UserAwareInterceptor.java:58)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.atlassian.confluence.pages.actions.CommentAwareInterceptor.intercept(CommentAwareInterceptor.java:43)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.atlassian.confluence.pages.actions.PageAwareInterceptor.intercept(PageAwareInterceptor.java:106)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.atlassian.confluence.spaces.actions.SpaceAwareInterceptor.intercept(SpaceAwareInterceptor.java:68)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
   	at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)
   	at com.atlassian.confluence.core.actions.LastModifiedInterceptor.intercept(LastModifiedI
   

Workaround

Use the old xwork until Atlassian fixes the problem.