diff --git a/admin-dev/ajaxfilemanager/inc/class.image.php b/admin-dev/ajaxfilemanager/inc/class.image.php
index dfbaf970c..c10230f83 100755
--- a/admin-dev/ajaxfilemanager/inc/class.image.php
+++ b/admin-dev/ajaxfilemanager/inc/class.image.php
@@ -602,7 +602,8 @@
             ob_start();
             phpinfo();
             $buffer = ob_get_contents();
-            ob_end_clean();
+			if (ob_get_level() && ob_get_length() > 0)
+				ob_end_clean();
             foreach (explode("\n", $buffer) as $line) {
                 $line = array_map('trim', (explode('|', strip_tags(str_replace('</td>', '|', $line)))));
                 if (isset($gd[$line[0]])) {
diff --git a/admin-dev/backup.php b/admin-dev/backup.php
index 8a4f66fef..eb9cc67b3 100644
--- a/admin-dev/backup.php
+++ b/admin-dev/backup.php
@@ -64,7 +64,8 @@ if ($fp === false)
 header('Content-Type: '.$contentType);
 header('Content-Disposition: attachment; filename="'.Tools::getValue('filename'). '"');
 
-ob_clean();
+if (ob_get_level() && ob_get_length() > 0)
+	ob_clean();
 $ret = @fpassthru($fp);
 
 fclose($fp);
diff --git a/admin-dev/functions.php b/admin-dev/functions.php
index 83de585b5..4df9759f9 100644
--- a/admin-dev/functions.php
+++ b/admin-dev/functions.php
@@ -544,7 +544,8 @@ function runAdminTab($tab, $ajaxMode = false)
 					if($ajaxMode)
 					{
 						// If this is an XSS attempt, then we should only display a simple, secure page
-						ob_clean();
+						if (ob_get_level() && ob_get_length() > 0)
+							ob_clean();
 
 						// ${1} in the replacement string of the regexp is required, because the token may begin with a number and mix up with it (e.g. $17)
 						$url = preg_replace('/([&?]token=)[^&]*(&.*)?$/', '${1}'.$adminObj->token.'$2', $_SERVER['REQUEST_URI']);
@@ -559,7 +560,8 @@ function runAdminTab($tab, $ajaxMode = false)
 					else
 					{
 						// If this is an XSS attempt, then we should only display a simple, secure page
-						ob_clean();
+						if (ob_get_level() && ob_get_length() > 0)
+							ob_clean();
 
 						// ${1} in the replacement string of the regexp is required, because the token may begin with a number and mix up with it (e.g. $17)
 						$url = preg_replace('/([&?]token=)[^&]*(&.*)?$/', '${1}'.$adminObj->token.'$2', $_SERVER['REQUEST_URI']);
diff --git a/classes/module/ModuleGraph.php b/classes/module/ModuleGraph.php
index 5790a92e5..cc03ca7e6 100644
--- a/classes/module/ModuleGraph.php
+++ b/classes/module/ModuleGraph.php
@@ -222,7 +222,7 @@ abstract class ModuleGraphCore extends Module
 
 	protected function _displayCsv()
 	{
-		if (ob_get_length())
+		if (ob_get_level() && ob_get_length() > 0)
 			ob_end_clean();
 		header('Content-Type: application/octet-stream');
 		header('Content-Disposition: attachment; filename="'.$this->displayName.' - '.time().'.csv"');
diff --git a/classes/module/ModuleGrid.php b/classes/module/ModuleGrid.php
index 7d3ab191a..fedfed49e 100644
--- a/classes/module/ModuleGrid.php
+++ b/classes/module/ModuleGrid.php
@@ -164,7 +164,8 @@ abstract class ModuleGridCore extends Module
 
 	protected function _displayCsv()
 	{
-		ob_end_clean();
+		if (ob_get_level() && ob_get_length() > 0)
+			ob_end_clean();
 		header('Content-Type: application/octet-stream');
 		header('Content-Disposition: attachment; filename="'.$this->displayName.' - '.time().'.csv"');
 		echo $this->_csv;
diff --git a/controllers/admin/AdminCustomerThreadsController.php b/controllers/admin/AdminCustomerThreadsController.php
index 2feec12bc..3d4937965 100644
--- a/controllers/admin/AdminCustomerThreadsController.php
+++ b/controllers/admin/AdminCustomerThreadsController.php
@@ -463,8 +463,9 @@ class AdminCustomerThreadsControllerCore extends AdminController
 
 		if (!$extension || !Validate::isFileName($filename))
 			die(Tools::displayError());
-			
-		ob_end_clean();
+
+		if (ob_get_level() && ob_get_length() > 0)
+			ob_end_clean();
 		header('Content-Type: '.$extension);
 		header('Content-Disposition:attachment;filename="'.$filename.'"');
 		readfile(_PS_UPLOAD_DIR_.$filename);
diff --git a/controllers/admin/AdminImportController.php b/controllers/admin/AdminImportController.php
index e97e3645e..41e4bd9b4 100644
--- a/controllers/admin/AdminImportController.php
+++ b/controllers/admin/AdminImportController.php
@@ -3120,7 +3120,8 @@ class AdminImportControllerCore extends AdminController
 						$mimeType = $mimeTypes[$bName];
 					else
 						$mimeType = 'application/octet-stream';
-					if (ob_get_level()) 
+					
+					if (ob_get_level() && ob_get_length() > 0)
 						ob_end_clean();
 	
 					header('Content-Transfer-Encoding: binary');
diff --git a/controllers/front/AttachmentController.php b/controllers/front/AttachmentController.php
index 8461be1f5..4244441eb 100644
--- a/controllers/front/AttachmentController.php
+++ b/controllers/front/AttachmentController.php
@@ -34,7 +34,7 @@ class AttachmentControllerCore extends FrontController
 
 		Hook::exec('actionDownloadAttachment', array('attachment' => &$a);
 
-		if (ob_get_level()) 
+		if (ob_get_level() && ob_get_length() > 0)
 			ob_end_clean();
 
 		header('Content-Transfer-Encoding: binary');
diff --git a/controllers/front/GetFileController.php b/controllers/front/GetFileController.php
index f39990b4d..d89f6c109 100644
--- a/controllers/front/GetFileController.php
+++ b/controllers/front/GetFileController.php
@@ -270,7 +270,7 @@ class GetFileControllerCore extends FrontController
 				$mimeType = 'application/octet-stream';
 		}
 
-		if (ob_get_level()) 
+		if (ob_get_level() && ob_get_length() > 0)
 			ob_end_clean();
 
 		/* Set headers for download */
diff --git a/install-dev/classes/controllerHttp.php b/install-dev/classes/controllerHttp.php
index 53bc10f39..d7c4e9b86 100644
--- a/install-dev/classes/controllerHttp.php
+++ b/install-dev/classes/controllerHttp.php
@@ -417,7 +417,8 @@ abstract class InstallControllerHttp
 		if ($get_output)
 		{
 			$content = ob_get_contents();
-			ob_end_clean();
+			if (ob_get_level() && ob_get_length() > 0)
+				ob_end_clean();
 			return $content;
 		}
 	}
diff --git a/install-dev/controllers/http/smarty_compile.php b/install-dev/controllers/http/smarty_compile.php
index e8374410c..901ab7a77 100644
--- a/install-dev/controllers/http/smarty_compile.php
+++ b/install-dev/controllers/http/smarty_compile.php
@@ -40,4 +40,5 @@ require_once(_PS_ROOT_DIR_.'/config/smarty.config.inc.php');
 $smarty->setTemplateDir($directory);
 ob_start();
 $smarty->compileAllTemplates('.tpl', false);
-ob_end_clean();
\ No newline at end of file
+if (ob_get_level() && ob_get_length() > 0)
+	ob_end_clean();
\ No newline at end of file