diff --git a/app/assets/javascripts/discourse/components/composer-editor.js.es6 b/app/assets/javascripts/discourse/components/composer-editor.js.es6
index 86a9b02e501..43d33da68fa 100644
--- a/app/assets/javascripts/discourse/components/composer-editor.js.es6
+++ b/app/assets/javascripts/discourse/components/composer-editor.js.es6
@@ -37,10 +37,19 @@ export default Ember.Component.extend({
     return `[${I18n.t('uploading')}]() `;
   },
 
-  @computed()
-  replyPlaceholder() {
-    const key = authorizesOneOrMoreImageExtensions() ? "reply_placeholder" : "reply_placeholder_no_images";
-    return `composer.${key}`;
+  @computed('composer.requiredCategoryMissing')
+  replyPlaceholder(requiredCategoryMissing) {
+    if (requiredCategoryMissing) {
+      return 'composer.reply_placeholder_choose_category';
+    } else {
+      const key = authorizesOneOrMoreImageExtensions() ? "reply_placeholder" : "reply_placeholder_no_images";
+      return `composer.${key}`;
+    }
+  },
+
+  @computed('composer.requiredCategoryMissing', 'composer.replyLength')
+  disableTextarea(requiredCategoryMissing, replyLength) {
+    return requiredCategoryMissing && replyLength === 0;
   },
 
   @observes('composer.uploadCancelled')
diff --git a/app/assets/javascripts/discourse/components/d-editor.js.es6 b/app/assets/javascripts/discourse/components/d-editor.js.es6
index e59ac9d78f1..c2811e5e5a3 100644
--- a/app/assets/javascripts/discourse/components/d-editor.js.es6
+++ b/app/assets/javascripts/discourse/components/d-editor.js.es6
@@ -750,6 +750,8 @@ export default Ember.Component.extend({
     },
 
     toolbarButton(button) {
+      if (this.get('disabled')) { return; }
+
       const selected = this._getSelected(button.trimLeading);
       const toolbarEvent = {
         selected,
@@ -770,6 +772,8 @@ export default Ember.Component.extend({
     },
 
     showLinkModal() {
+      if (this.get('disabled')) { return; }
+
       this._lastSel = this._getSelected();
 
       if (this._lastSel) {
@@ -780,6 +784,8 @@ export default Ember.Component.extend({
     },
 
     formatCode() {
+      if (this.get('disabled')) { return; }
+
       const sel = this._getSelected('', { lineVal: true });
       const selValue = sel.value;
       const hasNewLine = selValue.indexOf("\n") !== -1;
@@ -833,6 +839,7 @@ export default Ember.Component.extend({
     },
 
     emoji() {
+      if (this.get('disabled')) { return; }
       this.set('emojiPickerIsActive', !this.get('emojiPickerIsActive'));
     }
   }
diff --git a/app/assets/javascripts/discourse/models/composer.js.es6 b/app/assets/javascripts/discourse/models/composer.js.es6
index 52411269e6d..94a3e328001 100644
--- a/app/assets/javascripts/discourse/models/composer.js.es6
+++ b/app/assets/javascripts/discourse/models/composer.js.es6
@@ -265,13 +265,17 @@ const Composer = RestModel.extend({
       return this.get('targetUsernames') && (this.get('targetUsernames').trim() + ',').indexOf(',') === 0;
     } else {
       // has a category? (when needed)
-      return this.get('canCategorize') &&
-            !this.siteSettings.allow_uncategorized_topics &&
-            !this.get('categoryId') &&
-            !this.user.get('admin');
+      return this.get('requiredCategoryMissing');
     }
   }.property('loading', 'canEditTitle', 'titleLength', 'targetUsernames', 'replyLength', 'categoryId', 'missingReplyCharacters'),
 
+  @computed('canCategorize', 'categoryId')
+  requiredCategoryMissing(canCategorize, categoryId) {
+    return canCategorize && !categoryId &&
+      !this.siteSettings.allow_uncategorized_topics &&
+      !this.user.get('admin');
+  },
+
   titleLengthValid: function() {
     if (this.user.get('admin') && this.get('post.static_doc') && this.get('titleLength') > 0) return true;
     if (this.get('titleLength') < this.get('minimumTitleLength')) return false;
diff --git a/app/assets/javascripts/discourse/templates/components/composer-editor.hbs b/app/assets/javascripts/discourse/templates/components/composer-editor.hbs
index 511961d8f14..ebf9a3d856f 100644
--- a/app/assets/javascripts/discourse/templates/components/composer-editor.hbs
+++ b/app/assets/javascripts/discourse/templates/components/composer-editor.hbs
@@ -16,6 +16,7 @@
   onExpandPopupMenuOptions="onExpandPopupMenuOptions"
   onPopupMenuAction=onPopupMenuAction
   popupMenuOptions=popupMenuOptions
+  disabled=disableTextarea
   outletArgs=(hash composer=composer editorType="composer")}}
 
 {{#if site.mobileView}}
diff --git a/app/assets/javascripts/discourse/templates/components/d-editor.hbs b/app/assets/javascripts/discourse/templates/components/d-editor.hbs
index 06c636c2b7c..571285df208 100644
--- a/app/assets/javascripts/discourse/templates/components/d-editor.hbs
+++ b/app/assets/javascripts/discourse/templates/components/d-editor.hbs
@@ -10,7 +10,7 @@
 
 <div class='d-editor-container'>
   <div class="d-editor-textarea-wrapper">
-    <div class='d-editor-button-bar'>
+    <div class='d-editor-button-bar {{if disabled "disabled"}}'>
       {{#each toolbar.groups as |group|}}
         {{#each group.buttons as |b|}}
           {{#if b.popupMenu}}
@@ -39,7 +39,7 @@
     </div>
 
     {{conditional-loading-spinner condition=loading}}
-    {{textarea tabindex=tabindex value=value class="d-editor-input" placeholder=placeholderTranslated}}
+    {{textarea tabindex=tabindex value=value class="d-editor-input" placeholder=placeholderTranslated disabled=disabled}}
     {{popup-input-tip validation=validation}}
     {{plugin-outlet name="after-d-editor" tagName="" args=outletArgs}}
   </div>
diff --git a/app/assets/stylesheets/common/d-editor.scss b/app/assets/stylesheets/common/d-editor.scss
index f5a32ca1ece..7bf2b433f57 100644
--- a/app/assets/stylesheets/common/d-editor.scss
+++ b/app/assets/stylesheets/common/d-editor.scss
@@ -90,6 +90,11 @@
   .btn.italic {
     font-style: italic;
   }
+
+  &.disabled {
+    visibility: hidden;
+    cursor: not-allowed;
+  }
 }
 
 .d-editor-spacer {
diff --git a/config/locales/client.en.yml b/config/locales/client.en.yml
index d65cc600fe8..a3c56dd2594 100644
--- a/config/locales/client.en.yml
+++ b/config/locales/client.en.yml
@@ -1325,6 +1325,7 @@ en:
       remove_featured_link: "Remove link from topic."
       reply_placeholder: "Type here. Use Markdown, BBCode, or HTML to format. Drag or paste images."
       reply_placeholder_no_images: "Type here. Use Markdown, BBCode, or HTML to format."
+      reply_placeholder_choose_category: "Please select a category."
       view_new_post: "View your new post."
       saving: "Saving"
       saved: "Saved!"
diff --git a/test/javascripts/acceptance/composer-test.js.es6 b/test/javascripts/acceptance/composer-test.js.es6
index e35505eca67..c159485336b 100644
--- a/test/javascripts/acceptance/composer-test.js.es6
+++ b/test/javascripts/acceptance/composer-test.js.es6
@@ -1,4 +1,4 @@
-import { acceptance } from "helpers/qunit-helpers";
+import { acceptance, replaceCurrentUser } from "helpers/qunit-helpers";
 
 acceptance("Composer", {
   loggedIn: true,
@@ -335,3 +335,42 @@ QUnit.test("Composer draft with dirty reply can toggle to edit", assert => {
     assert.equal(find('.d-editor-input').val().indexOf('This is the first post.'), 0, 'it populates the input with the post text');
   });
 });
+
+acceptance("Composer and uncategorized is not allowed", {
+  loggedIn: true,
+  settings: {
+    enable_whispers: true,
+    allow_uncategorized_topics: false
+  }
+});
+
+QUnit.test("Disable body until category is selected", assert => {
+  replaceCurrentUser({ admin: false, staff: false, trust_level: 1 });
+
+  visit("/");
+  click('#create-topic');
+  andThen(() => {
+    assert.ok(exists('.d-editor-input'), 'the composer input is visible');
+    assert.ok(exists('.title-input .popup-tip.bad.hide'), 'title errors are hidden by default');
+    assert.ok(exists('.d-editor-textarea-wrapper .popup-tip.bad.hide'), 'body errors are hidden by default');
+    assert.ok(exists('.d-editor-container .d-editor-button-bar.disabled'), 'toolbar is disabled');
+    assert.ok(find('.d-editor-container .d-editor-input:disabled').length, 'textarea is disabled');
+  });
+
+  const categoryChooser = selectKit('.category-chooser');
+
+  categoryChooser.expand().selectRowByValue(2);
+
+  andThen(() => {
+    assert.ok(!exists('.d-editor-container .d-editor-button-bar.disabled'), 'toolbar is enabled');
+    assert.ok(find('.d-editor-container .d-editor-input:disabled').length === 0, 'textarea is enabled');
+  });
+
+  fillIn('.d-editor-input', 'Now I can type stuff');
+  categoryChooser.expand().selectRowByValue('__none__');
+
+  andThen(() => {
+    assert.ok(!exists('.d-editor-container .d-editor-button-bar.disabled'), 'toolbar is still enabled');
+    assert.ok(find('.d-editor-container .d-editor-input:disabled').length === 0, 'textarea is still enabled');
+  });
+});
diff --git a/test/javascripts/acceptance/composer-topic-links-test.js.es6 b/test/javascripts/acceptance/composer-topic-links-test.js.es6
index d8083623f26..c57464d11ef 100644
--- a/test/javascripts/acceptance/composer-topic-links-test.js.es6
+++ b/test/javascripts/acceptance/composer-topic-links-test.js.es6
@@ -1,4 +1,4 @@
-import { acceptance } from "helpers/qunit-helpers";
+import { acceptance, replaceCurrentUser } from "helpers/qunit-helpers";
 
 acceptance("Composer topic featured links", {
   loggedIn: true,
@@ -76,3 +76,32 @@ QUnit.test("onebox with title but extra words in title field", assert => {
     assert.equal(find('.title-input input').val(), "http://www.example.com/has-title.html test", "title is unchanged");
   });
 });
+
+acceptance("Composer topic featured links when uncategorized is not allowed", {
+  loggedIn: true,
+  settings: {
+    topic_featured_link_enabled: true,
+    max_topic_title_length: 80,
+    enable_markdown_linkify: true,
+    allow_uncategorized_topics: false
+  }
+});
+
+QUnit.test("Pasting a link enables the text input area", assert => {
+  replaceCurrentUser({ admin: false, staff: false, trust_level: 1 });
+
+  visit("/");
+  click('#create-topic');
+  andThen(() => {
+    assert.ok(exists('.d-editor-container .d-editor-button-bar.disabled'), 'toolbar is disabled');
+    assert.ok(find('.d-editor-container .d-editor-input:disabled').length, 'textarea is disabled');
+  });
+  fillIn('#reply-title', "http://www.example.com/has-title.html");
+  andThen(() => {
+    assert.ok(find('.d-editor-preview').html().trim().indexOf('onebox') > 0, "it pastes the link into the body and previews it");
+    assert.ok(exists('.d-editor-textarea-wrapper .popup-tip.good'), 'the body is now good');
+    assert.equal(find('.title-input input').val(), "An interesting article", "title is from the oneboxed article");
+    assert.ok(!exists('.d-editor-container .d-editor-button-bar.disabled'), 'toolbar is enabled');
+    assert.ok(find('.d-editor-container .d-editor-input:disabled').length === 0, 'textarea is enabled');
+  });
+});