diff --git a/src/octoprint/static/js/app/viewmodels/files.js b/src/octoprint/static/js/app/viewmodels/files.js
index 5da2cd3a..6b94f997 100644
--- a/src/octoprint/static/js/app/viewmodels/files.js
+++ b/src/octoprint/static/js/app/viewmodels/files.js
@@ -841,13 +841,14 @@ $(function() {
 
             function evaluateDropzones() {
                 var enableLocal = self.loginState.isUser();
-                var enableSd = enableLocal && CONFIG_SD_SUPPORT && self.printerState.isSdReady();
+                var enableSd = enableLocal && CONFIG_SD_SUPPORT && self.printerState.isSdReady() && !self.isPrinting();
 
                 self._setDropzone("local", enableLocal);
                 self._setDropzone("sdcard", enableSd);
             }
             self.loginState.isUser.subscribe(evaluateDropzones);
             self.printerState.isSdReady.subscribe(evaluateDropzones);
+            self.isPrinting.subscribe(evaluateDropzones);
             evaluateDropzones();
 
             self.requestData();
@@ -1106,7 +1107,7 @@ $(function() {
             if (foundLocal) {
                 self.dropZoneLocalBackground.addClass("hover");
                 self.dropZoneSdBackground.removeClass("hover");
-            } else if (foundSd && self.printerState.isSdReady()) {
+            } else if (foundSd && self.printerState.isSdReady() && !self.isPrinting()) {
                 self.dropZoneSdBackground.addClass("hover");
                 self.dropZoneLocalBackground.removeClass("hover");
             } else if (found) {
diff --git a/src/octoprint/templates/overlays/dragndrop.jinja2 b/src/octoprint/templates/overlays/dragndrop.jinja2
index 91a74a38..bb67ae1b 100644
--- a/src/octoprint/templates/overlays/dragndrop.jinja2
+++ b/src/octoprint/templates/overlays/dragndrop.jinja2
@@ -4,7 +4,7 @@
         {% if enableSdSupport %}
             <div class="dropzone" id="drop_locally"><span class="text"><i class="icon-upload-alt"></i><br>{{ _('Upload locally') }}</span></div>
             <div class="dropzone_background" id="drop_locally_background"></div>
-            <div class="dropzone" id="drop_sd"><span class="text"><i class="icon-upload-alt"></i><br>{{ _('Upload to SD') }}<br><small data-bind="visible: !isSdReady()">({{ _('SD not initialized') }})</small></span></div>
+            <div class="dropzone" id="drop_sd"><span class="text"><i class="icon-upload-alt"></i><br>{{ _('Upload to SD') }}<br><small data-bind="visible: isSdReady() && isPrinting()">({{ _('Cannot upload to printer\'s SD while printing') }})</small><small data-bind="visible: !isSdReady()">({{ _('SD not initialized') }})</small></span></div>
             <div class="dropzone_background" id="drop_sd_background"></div>
         {% else %}
             <div class="dropzone" id="drop"><span class="text"><i class="icon-upload-alt"></i><br>{{ _('Upload') }}</span></div>
diff --git a/src/octoprint/templates/sidebar/files.jinja2 b/src/octoprint/templates/sidebar/files.jinja2
index 99b199df..4a06d7d7 100644
--- a/src/octoprint/templates/sidebar/files.jinja2
+++ b/src/octoprint/templates/sidebar/files.jinja2
@@ -55,18 +55,18 @@
     </div>
     <div class="row-fluid upload-buttons">
         {% if enableSdSupport %}
-            <span class="btn btn-primary fileinput-button span6" data-bind="css: {disabled: !$root.loginState.isUser()}" style="margin-bottom: 10px">
+            <span class="btn btn-primary fileinput-button span6" data-bind="enable: $root.loginState.isUser(), css: {disabled: !$root.loginState.isUser()}" style="margin-bottom: 10px">
                                 <i class="icon-upload-alt icon-white"></i>
                                 <span>{{ _('Upload') }}</span>
                                 <input id="gcode_upload" accept="{{ ",".join(supportedExtensions) }}" type="file" name="file" class="fileinput-button" data-bind="enable: loginState.isUser()">
                             </span>
-            <span class="btn btn-primary fileinput-button span6" data-bind="css: {disabled: !$root.loginState.isUser() || !$root.isSdReady()}" style="margin-bottom: 10px">
+            <span class="btn btn-primary fileinput-button span6" data-bind="enable: $root.loginState.isUser() && $root.isSdReady() && !$root.isPrinting(), css: {disabled: !$root.loginState.isUser() || !$root.isSdReady() || $root.isPrinting()}" style="margin-bottom: 10px">
                                 <i class="icon-upload-alt icon-white"></i>
                                 <span>{{ _('Upload to SD') }}</span>
-                                <input id="gcode_upload_sd" accept="{{ ",".join(supportedExtensions) }}" type="file" name="file" class="fileinput-button" data-bind="enable: loginState.isUser() && isSdReady()">
+                                <input id="gcode_upload_sd" accept="{{ ",".join(supportedExtensions) }}" type="file" name="file" class="fileinput-button" data-bind="enable: loginState.isUser() && isSdReady() && !isPrinting()">
                             </span>
         {% else %}
-            <span class="btn btn-primary fileinput-button span12" data-bind="css: {disabled: !$root.loginState.isUser()}" style="margin-bottom: 10px">
+            <span class="btn btn-primary fileinput-button span12" data-bind="enable: $root.loginState.isUser(), css: {disabled: !$root.loginState.isUser()}" style="margin-bottom: 10px">
                                 <i class="icon-upload-alt icon-white"></i>
                                 <span>{{ _('Upload') }}</span>
                                 <input id="gcode_upload" accept="{{ ",".join(supportedExtensions) }}" type="file" name="file" class="fileinput-button" data-bind="enable: loginState.isUser()">