diff --git a/htdocs/core/ajax/flowjs-server.php b/htdocs/core/ajax/flowjs-server.php
index cb66ad884ae..918871421d3 100644
--- a/htdocs/core/ajax/flowjs-server.php
+++ b/htdocs/core/ajax/flowjs-server.php
@@ -80,7 +80,10 @@ if ($_SERVER['REQUEST_METHOD'] === 'GET') {
 	}
 } else {
 	// loop through files and move the chunks to a temporarily created directory
-	if (!empty($_FILES)) foreach ($_FILES as $file) {
+	if (file_exists($upload_dir.'/'.$flowFilename)) {
+		echo json_encode('File '.$flowIdentifier.' was already uploaded');
+		header("HTTP/1.0 200 Ok");
+	} else if (!empty($_FILES)) foreach ($_FILES as $file) {
 		// check the error status
 		if ($file['error'] != 0) {
 			dol_syslog('error '.$file['error'].' in file '.$flowFilename);