diff --git a/webadmin/src/js/setup.js b/webadmin/src/js/setup.js
index 64e657f17..489f5d67d 100644
--- a/webadmin/src/js/setup.js
+++ b/webadmin/src/js/setup.js
@@ -23,16 +23,20 @@ app.controller('SetupController', ['$scope', '$http', 'Client', function ($scope
 
     $scope.activateCloudron = function () {
         $scope.busy = true;
+        $scope.error = null;
 
         Client.createAdmin($scope.account.username, $scope.account.password, $scope.account.email, $scope.account.displayName, $scope.setupToken, function (error) {
-            if (error && error.statusCode === 403) {
+            if (error && error.statusCode === 400) {
                 $scope.busy = false;
-                $scope.error = $scope.provider === 'ami' ? 'Wrong instance id' : 'Wrong setup token';
+                $scope.error = { username: error.message };
+                $scope.account.username = '';
+                $scope.setupForm.username.$setPristine();
+                setTimeout(function () { $('#inputUsername').focus(); }, 200);
                 return;
             } else if (error) {
                 $scope.busy = false;
                 console.error('Internal error', error);
-                $scope.error = error;
+                $scope.error = { generic: error.message };
                 return;
             }
 
diff --git a/webadmin/src/setup.html b/webadmin/src/setup.html
index 1e68e4586..e1c8a583d 100644
--- a/webadmin/src/setup.html
+++ b/webadmin/src/setup.html
@@ -72,7 +72,8 @@
                                 <div ng-show="account.requireEmail" class="form-group" ng-class="{ 'has-error': setupForm.email.$dirty && setupForm.email.$invalid }">
                                     <input type="email" class="form-control" ng-model="account.email" id="inputEmail" name="email" placeholder="Email" required autocomplete="off" tooltip-trigger="focus" uib-tooltip="This email address is local to your Cloudron and used for notifications and password reset.">
                                 </div>
-                                <div class="form-group" ng-class="{ 'has-error': setupForm.username.$dirty && setupForm.username.$invalid }">
+                                <div class="form-group" ng-class="{ 'has-error': (setupForm.username.$dirty && setupForm.username.$invalid) || (!setupForm.username.$dirty && error.username) }">
+                                    <p ng-show="!setupForm.username.$dirty && error.username">{{ error.username }}</p>
                                     <input type="text" class="form-control" ng-model="account.username" id="inputUsername" name="username" placeholder="Username" ng-maxlength="512" ng-minlength="3" required autocomplete="off">
                                 </div>
                                 <div class="form-group" ng-class="{ 'has-error': setupForm.password.$dirty && setupForm.password.$invalid }">