diff --git a/changelog.html b/changelog.html
index f16432cb055432a5b42506c495cf5e355324aba1..b31454c907eaae37cedb98fbe5eb3b359c35b9c9 100644
--- a/changelog.html
+++ b/changelog.html
@@ -58,7 +58,9 @@ Upcoming changes</a>
   <li class=bug>
    Fixed: Human readable file size method returns ",00" for files with byte length 0
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-16630">issue 16630</a>)
-
+  <li class=bug>
+    “Build” from job context menu produced a confusing warning page.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-16844">issue 16844</a>)
 </ul>
 </div><!--=TRUNK-END=-->
 
diff --git a/core/src/main/java/jenkins/model/ModelObjectWithContextMenu.java b/core/src/main/java/jenkins/model/ModelObjectWithContextMenu.java
index 1f501f7746d5d4d30a1c55765ed2d1b93f694801..598cd40b20a65e8926af04395633a0ff2e330eea 100644
--- a/core/src/main/java/jenkins/model/ModelObjectWithContextMenu.java
+++ b/core/src/main/java/jenkins/model/ModelObjectWithContextMenu.java
@@ -95,6 +95,16 @@ public interface ModelObjectWithContextMenu extends ModelObject {
             return this;
         }
 
+        /** @since 1.504 */
+        public ContextMenu add(String url, String icon, String text, boolean post) {
+            if (text != null && icon != null && url != null) {
+                MenuItem item = new MenuItem(url,icon,text);
+                item.post = post;
+                items.add(item);
+            }
+            return this;
+        }
+
         /**
          * Default implementation of the context menu generation.
          * 
@@ -167,6 +177,12 @@ public interface ModelObjectWithContextMenu extends ModelObject {
         @Exported
         public String icon;
 
+        /**
+         * True to make a POST request rather than GET.
+         * @since 1.504
+         */
+        @Exported public boolean post;
+
         /**
          * If this is a submenu, definition of subitems.
          */
diff --git a/core/src/main/resources/hudson/model/AbstractProject/sidepanel.jelly b/core/src/main/resources/hudson/model/AbstractProject/sidepanel.jelly
index defffae8c1fa0902ed2a47caf1c35fba9d8b0426..4cc0c0ad2747f2bc2dfa9de44e1d99de55b11bc5 100644
--- a/core/src/main/resources/hudson/model/AbstractProject/sidepanel.jelly
+++ b/core/src/main/resources/hudson/model/AbstractProject/sidepanel.jelly
@@ -46,7 +46,7 @@ THE SOFTWARE.
       <j:if test="${it.configurable}">
         <j:if test="${it.buildable}">
           <l:task icon="images/24x24/clock.png" href="${url}/build?delay=0sec" title="${it.buildNowText}"
-                  onclick="${it.parameterized?null:'return build(this)'}" permission="${it.BUILD}" />
+                  onclick="${it.parameterized?null:'return build(this)'}" post="true" permission="${it.BUILD}"/>
           <script>
             function build(a) {
               new Ajax.Request(a.href);
diff --git a/core/src/main/resources/lib/layout/breadcrumbs.js b/core/src/main/resources/lib/layout/breadcrumbs.js
index 394b600093f5d808d0db8cb225cacb29206c0ce4..98d870fc3c1512642316929db47d4fb44dc226f6 100644
--- a/core/src/main/resources/lib/layout/breadcrumbs.js
+++ b/core/src/main/resources/lib/layout/breadcrumbs.js
@@ -66,6 +66,13 @@ var breadcrumbs = (function() {
         return a+'/'+b+qs;
     }
 
+    function postRequest(action, event, url) {
+        new Ajax.Request(url);
+        if (event.length == 1 && event[0].target != null) {
+            hoverNotification('Done.', event[0].target);
+        }
+    }
+
     /**
      * Called when the mouse cursor comes into the context menu hot spot.
      *
@@ -111,6 +118,10 @@ var breadcrumbs = (function() {
                         e.text = makeMenuHtml(e.icon, e.displayName);
                         if (e.subMenu!=null)
                             e.subMenu = {id:"submenu"+(iota++), itemdata:e.subMenu.items.each(fillMenuItem)};
+                        if (e.post) {
+                            e.onclick = {fn: postRequest, obj: e.url};
+                            delete e.url;
+                        }
                     }
                     a.each(fillMenuItem);
 
diff --git a/core/src/main/resources/lib/layout/task.jelly b/core/src/main/resources/lib/layout/task.jelly
index b5839985dc9738e56925317899e5108f8f776991..9ffd0791f7644a416f4653c13c2429ff27a7d463 100644
--- a/core/src/main/resources/lib/layout/task.jelly
+++ b/core/src/main/resources/lib/layout/task.jelly
@@ -56,6 +56,11 @@ THE SOFTWARE.
       This is useful for showing links to restricted pages, as showing
       them to unprivileged users don't make sense.
     </st:attribute>
+    <st:attribute name="post" type="boolean">
+      If true, send a POST rather than a GET request.
+      (onclick supersedes this except in the context menu.)
+      (since 1.504)
+    </st:attribute>
   </st:documentation>
 
   <!--
@@ -98,14 +103,24 @@ THE SOFTWARE.
       <j:otherwise>
         <div class="task">
           <j:set var="icon" value="${rootURL}${icon.startsWith('images/') || icon.startsWith('plugin/') ? h.resourcePath : ''}/${icon}"/>
-          ${taskTags!=null and attrs.contextMenu!='false' ? taskTags.add(href,icon,title) : null}
+          ${taskTags!=null and attrs.contextMenu!='false' ? taskTags.add(href, icon, title, post == 'true') : null}
+
+          <j:if test="${attrs.onclick == null &amp;&amp; post}">
+              <script>
+                  function postRequest(a) {
+                      new Ajax.Request(a.href);
+                      hoverNotification('${%Done.}', a.parentNode);
+                      return false;
+                  }
+              </script>
+          </j:if>
 
-          <a href="${href}" onclick="${attrs.onclick}">
+          <a href="${href}" onclick="${attrs.onclick ?: (post ? 'postRequest(this)' : null)}">
             <img width="24" height="24" style="margin: 2px;" alt="" src="${icon}"/>
           </a>
           <st:nbsp />
 
-          <a href="${href}" onclick="${attrs.onclick}">
+          <a href="${href}" onclick="${attrs.onclick ?: (post ? 'postRequest(this)' : null)}">
             <j:choose>
               <j:when test="${match}">
                 <b>${title}</b>