diff --git a/htdocs/api/class/api_documents.class.php b/htdocs/api/class/api_documents.class.php
index 48d6bf5b903..1b98ad5f2ec 100644
--- a/htdocs/api/class/api_documents.class.php
+++ b/htdocs/api/class/api_documents.class.php
@@ -56,7 +56,7 @@ class Documents extends DolibarrApi
 	 * Note that, this API is similar to using the wrapper link "documents.php" to download a file (used for
 	 * internal HTML links of documents into application), but with no need to have a session cookie (the token is used instead).
 	 *
-	 * @param   string  $module_part    Name of module or area concerned by file download ('facture', ...)
+	 * @param   string  $modulepart     Name of module or area concerned by file download ('facture', ...)
 	 * @param   string  $original_file  Relative path with filename, relative to modulepart (for example: IN201701-999/IN201701-999.pdf)
 	 * @return  array                   List of documents
 	 *
@@ -67,11 +67,11 @@ class Documents extends DolibarrApi
 	 *
 	 * @url GET /download
 	 */
-	public function index($module_part, $original_file = '')
+	public function index($modulepart, $original_file = '')
 	{
 		global $conf, $langs;
 
-		if (empty($module_part)) {
+		if (empty($modulepart)) {
 				throw new RestException(400, 'bad value for parameter modulepart');
 		}
 		if (empty($original_file)) {
@@ -81,7 +81,7 @@ class Documents extends DolibarrApi
 		//--- Finds and returns the document
 		$entity=$conf->entity;
 
-		$check_access = dol_check_secure_access_document($module_part, $original_file, $entity, DolibarrApiAccess::$user, '', 'read');
+		$check_access = dol_check_secure_access_document($modulepart, $original_file, $entity, DolibarrApiAccess::$user, '', 'read');
 		$accessallowed = $check_access['accessallowed'];
 		$sqlprotectagainstexternals = $check_access['sqlprotectagainstexternals'];
 		$original_file = $check_access['original_file'];
@@ -98,6 +98,7 @@ class Documents extends DolibarrApi
 
 		if (! file_exists($original_file_osencoded))
 		{
+			dol_syslog("Try to download not found file ".$original_file_osencoded, LOG_WARNING);
 			throw new RestException(404, 'File not found');
 		}
 
@@ -111,7 +112,7 @@ class Documents extends DolibarrApi
 	 *
 	 * Test sample 1: { "module_part": "invoice", "original_file": "FA1701-001/FA1701-001.pdf", "doctemplate": "crabe", "langcode": "fr_FR" }.
 	 *
-	 * @param   string  $module_part    Name of module or area concerned by file download ('invoice', 'order', ...).
+	 * @param   string  $modulepart    Name of module or area concerned by file download ('invoice', 'order', ...).
 	 * @param   string  $original_file  Relative path with filename, relative to modulepart (for example: IN201701-999/IN201701-999.pdf).
 	 * @param	string	$doctemplate	Set here the doc template to use for document generation (If not set, use the default template).
 	 * @param	string	$langcode		Language code like 'en_US', 'fr_FR', 'es_ES', ... (If not set, use the default language).
@@ -126,11 +127,11 @@ class Documents extends DolibarrApi
 	 *
 	 * @url PUT /builddoc
 	 */
-	public function builddoc($module_part, $original_file = '', $doctemplate = '', $langcode = '')
+	public function builddoc($modulepart, $original_file = '', $doctemplate = '', $langcode = '')
 	{
 		global $conf, $langs;
 
-		if (empty($module_part)) {
+		if (empty($modulepart)) {
 			throw new RestException(400, 'bad value for parameter modulepart');
 		}
 		if (empty($original_file)) {
@@ -147,7 +148,7 @@ class Documents extends DolibarrApi
 		//--- Finds and returns the document
 		$entity=$conf->entity;
 
-		$check_access = dol_check_secure_access_document($module_part, $original_file, $entity, DolibarrApiAccess::$user, '', 'write');
+		$check_access = dol_check_secure_access_document($modulepart, $original_file, $entity, DolibarrApiAccess::$user, '', 'write');
 		$accessallowed              = $check_access['accessallowed'];
 		$sqlprotectagainstexternals = $check_access['sqlprotectagainstexternals'];
 		$original_file              = $check_access['original_file'];
@@ -166,7 +167,7 @@ class Documents extends DolibarrApi
 
 		$templateused='';
 
-		if ($module_part == 'facture' || $module_part == 'invoice')
+		if ($modulepart == 'facture' || $modulepart == 'invoice')
 		{
 			require_once DOL_DOCUMENT_ROOT.'/compta/facture/class/facture.class.php';
 			$this->invoice = new Facture($this->db);
@@ -181,7 +182,7 @@ class Documents extends DolibarrApi
 				throw new RestException(500, 'Error generating document');
 			}
 		}
-		elseif ($module_part == 'commande' || $module_part == 'order')
+		elseif ($modulepart == 'commande' || $modulepart == 'order')
 		{
 			require_once DOL_DOCUMENT_ROOT.'/commande/class/commande.class.php';
 			$this->order = new Commande($this->db);
@@ -195,7 +196,7 @@ class Documents extends DolibarrApi
 				throw new RestException(500, 'Error generating document');
 			}
 		}
-		elseif ($module_part == 'propal' || $module_part == 'proposal')
+		elseif ($modulepart == 'propal' || $modulepart == 'proposal')
 		{
 			require_once DOL_DOCUMENT_ROOT.'/comm/propal/class/propal.class.php';
 			$this->propal = new Propal($this->db);