diff --git a/themes/grav/templates/forms/fields/uploads/uploads.html.twig b/themes/grav/templates/forms/fields/uploads/uploads.html.twig
index 9951a50c..8fb46cb9 100644
--- a/themes/grav/templates/forms/fields/uploads/uploads.html.twig
+++ b/themes/grav/templates/forms/fields/uploads/uploads.html.twig
@@ -37,13 +37,24 @@
                         thisDropzone = this;
                         $.get(URI + '/task:listmedia', function(data) {
                             $.each(data, function(filename, data){
-                                var mockFile = { name: filename, size: data.size, extras: data };
+                                var mockFile = { name: filename, size: data.size, accepted: true, extras: data };
                                 thisDropzone.files.push(mockFile);
                                 thisDropzone.options.addedfile.call(thisDropzone, mockFile);
                                 thisDropzone.options.thumbnail.call(thisDropzone, mockFile, data.url);
                             });
                         });
 
+                        this.on("complete", function(file) {
+                            if (file.accepted) return;
+                            var data = {status: 'error', message: 'Unsupported file type: ' + file.name.match(/\..+/).join('')};
+                            $.proxy(modalError, this, {
+                                file: file,
+                                data: data,
+                                mode: 'removeFile',
+                                msg: '<p>An error occurred while trying to add the file <strong>'+file.name+'</strong></p><pre>'+data.message+'</pre>'
+                            })();
+                        });
+
                         this.on('success', function(file, response){
                             thisDropzone = this;
                             $.proxy(modalError, this, {
@@ -55,6 +66,7 @@
                         });
 
                         this.on('removedfile', function(file) {
+                            if (!file.accepted) return;
                             thisDropzone = this;
                             $.post(URI + '/task:delmedia', {filename: file.name}, function(data){
                                 $.proxy(modalError, thisDropzone, {