diff --git a/htdocs/core/class/html.formfile.class.php b/htdocs/core/class/html.formfile.class.php
index 9ed3a32d409..f45460edd4d 100644
--- a/htdocs/core/class/html.formfile.class.php
+++ b/htdocs/core/class/html.formfile.class.php
@@ -363,7 +363,7 @@ class FormFile
 			print ' type="submit" value="'.$buttonlabel.'"';
 			if (! $allowgenifempty && ! is_array($modellist) && empty($modellist)) print ' disabled="true"';
 			print '>';
-			if ($allowgenifempty && ! is_array($modellist) && empty($modellist))
+			if ($allowgenifempty && ! is_array($modellist) && empty($modellist) && $modulepart != 'unpaid')
 			{
 				$langs->load("errors");
 				print ' '.img_warning($langs->trans("WarningNoDocumentModelActivated"));