diff --git a/application/config/migration.php b/application/config/migration.php
index 6aa8233a..70841b48 100644
--- a/application/config/migration.php
+++ b/application/config/migration.php
@@ -21,7 +21,7 @@ $config['migration_enabled'] = TRUE;
 | be upgraded / downgraded to.
 |
 */
-$config['migration_version'] = 51;
+$config['migration_version'] = 52;
 
 /*
 |--------------------------------------------------------------------------
diff --git a/application/views/interface_assets/header.php b/application/views/interface_assets/header.php
index 89cb77a7..00deb9df 100644
--- a/application/views/interface_assets/header.php
+++ b/application/views/interface_assets/header.php
@@ -6,7 +6,11 @@
     <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
 
     <!-- Bootstrap CSS -->
-    <link rel="stylesheet" href="<?php echo base_url(); ?>assets/css/<?php echo $this->session->userdata('user_stylesheet');?>">
+    <?php if($this->session->userdata('user_stylesheet')) { ?>
+    	<link rel="stylesheet" href="<?php echo base_url(); ?>assets/css/<?php echo $this->session->userdata('user_stylesheet');?>">
+	<?php } else { ?>
+		<link rel="stylesheet" href="<?php echo base_url(); ?>assets/css/bootstrap.min.css">
+	<?php } ?>
     <link rel="stylesheet" href="<?php echo base_url(); ?>assets/fontawesome/css/all.css">
 
 	<link rel="stylesheet" href="<?php echo base_url(); ?>assets/css/jquery.fancybox.min.css" />
diff --git a/application/views/interface_assets/mini_header.php b/application/views/interface_assets/mini_header.php
index eea5e23c..a5766b9e 100644
--- a/application/views/interface_assets/mini_header.php
+++ b/application/views/interface_assets/mini_header.php
@@ -6,7 +6,11 @@
     <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
 
     <!-- Bootstrap CSS -->
-    <link rel="stylesheet" href="<?php echo base_url(); ?>assets/css/<?php echo $this->session->userdata('user_stylesheet');?>">
+    <?php if($this->session->userdata('user_stylesheet')) { ?>
+      <link rel="stylesheet" href="<?php echo base_url(); ?>assets/css/<?php echo $this->session->userdata('user_stylesheet');?>">
+    <?php } else { ?>
+      <link rel="stylesheet" href="<?php echo base_url(); ?>assets/css/bootstrap.min.css">
+    <?php } ?>
     <link rel="stylesheet" href="<?php echo base_url(); ?>assets/fontawesome/css/all.css">
 
 	   <link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/fancyapps/fancybox@3.5.7/dist/jquery.fancybox.min.css" />