From c6bebc815732d9de0c6ac7ea426469131c72e558 Mon Sep 17 00:00:00 2001
From: JimHeo <gjwlals111@gmail.com>
Date: Wed, 19 Feb 2025 15:41:27 +0900
Subject: [PATCH] fix: missing boundary in multipart/form-data error

---
 api/core/tools/custom_tool/tool.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/api/core/tools/custom_tool/tool.py b/api/core/tools/custom_tool/tool.py
index f8467c54c5..8a0163760e 100644
--- a/api/core/tools/custom_tool/tool.py
+++ b/api/core/tools/custom_tool/tool.py
@@ -211,6 +211,12 @@ class ApiTool(Tool):
                 body = urlencode(body)
             else:
                 body = body
+                
+        # if there is a file upload, remove the Content-Type header so that httpx can automatically generate the boundary header required for multipart/form-data.
+        # issue: https://github.com/langgenius/dify/issues/13684
+        # reference: https://stackoverflow.com/questions/39280438/fetch-missing-boundary-in-multipart-form-data-post
+        if files:
+            headers.pop("Content-Type", None)
 
         if method in {
             "get",