diff --git a/packages/spacebars-tests/template_tests.js b/packages/spacebars-tests/template_tests.js
index 3db4c1674e..c96153c4cb 100644
--- a/packages/spacebars-tests/template_tests.js
+++ b/packages/spacebars-tests/template_tests.js
@@ -675,6 +675,7 @@ Tinytest.add('spacebars - templates - no data context', function (test) {
 Tinytest.add('spacebars - templates - isolate', function (test) {
   var tmpl = Template.spacebars_template_test_isolate;
 
+  Meteor._suppress_log(1); // we print a deprecation notice
   var div = renderToDiv(tmpl);
   test.equal(canonicalizeHtml(div.innerHTML), 'hello');
 
@@ -684,6 +685,7 @@ Tinytest.add('spacebars - templates - isolate', function (test) {
 Tinytest.add('spacebars - templates - constant', function (test) {
   var tmpl = Template.spacebars_template_test_constant;
 
+  Meteor._suppress_log(1); // we print a deprecation notice
   var div = renderToDiv(tmpl);
   test.equal(canonicalizeHtml(div.innerHTML), 'hello');
 
diff --git a/packages/ui/base.js b/packages/ui/base.js
index 9b41ca0864..4352cfa96c 100644
--- a/packages/ui/base.js
+++ b/packages/ui/base.js
@@ -348,4 +348,6 @@ UI.Component.notifyParented = function () {
 };
 
 // past compat
-UI.Component.preserve = function () {};
+UI.Component.preserve = function () {
+  Meteor._debug("The 'preserve' method on templates is now unnecessary and deprecated.");
+};
diff --git a/packages/ui/fields.js b/packages/ui/fields.js
index fe454067f2..b95a13b9b1 100644
--- a/packages/ui/fields.js
+++ b/packages/ui/fields.js
@@ -12,20 +12,23 @@ var lookupComponentProp = function (comp, prop) {
 };
 
 // Component that's a no-op when used as a block helper like
-// `{{#foo}}...{{/foo}}`.
-var noOpComponent = Component.extend({
-  kind: 'NoOp',
-  render: function () {
-    return this.__content;
-  }
-});
+// `{{#foo}}...{{/foo}}`. Prints a warning that it is deprecated.
+var noOpComponent = function (name) {
+  return Component.extend({
+    kind: 'NoOp',
+    render: function () {
+      Meteor._debug("{{#" + name + "}} is now unnecessary and deprecated.");
+      return this.__content;
+    }
+  });
+};
 
 // This map is searched first when you do something like `{{#foo}}` in
 // a template.
 var builtInComponents = {
   // for past compat:
-  'constant': noOpComponent,
-  'isolate': noOpComponent
+  'constant': noOpComponent("constant"),
+  'isolate': noOpComponent("isolate")
 };
 
 _extend(UI.Component, {