diff --git a/api/core/rag/extractor/pdf_extractor.py b/api/core/rag/extractor/pdf_extractor.py
index 02f0efc908..25f6fe3e2a 100644
--- a/api/core/rag/extractor/pdf_extractor.py
+++ b/api/core/rag/extractor/pdf_extractor.py
@@ -115,7 +115,7 @@ class PdfExtractor(BaseExtractor):
         """
         image_content = []
         upload_files = []
-        base_url = dify_config.INTERNAL_FILES_URL or dify_config.FILES_URL
+        base_url = dify_config.FILES_URL
 
         try:
             image_objects = page.get_objects(filter=(pdfium_c.FPDF_PAGEOBJ_IMAGE,))
diff --git a/api/core/rag/extractor/word_extractor.py b/api/core/rag/extractor/word_extractor.py
index 0330a43b28..60f8906181 100644
--- a/api/core/rag/extractor/word_extractor.py
+++ b/api/core/rag/extractor/word_extractor.py
@@ -110,7 +110,7 @@ class WordExtractor(BaseExtractor):
     def _extract_images_from_docx(self, doc):
         image_count = 0
         image_map = {}
-        base_url = dify_config.INTERNAL_FILES_URL or dify_config.FILES_URL
+        base_url = dify_config.FILES_URL
 
         for r_id, rel in doc.part.rels.items():
             if "image" in rel.target_ref:
diff --git a/api/core/tools/signature.py b/api/core/tools/signature.py
index 1807226924..e8281fd9d4 100644
--- a/api/core/tools/signature.py
+++ b/api/core/tools/signature.py
@@ -26,12 +26,12 @@ def sign_tool_file(tool_file_id: str, extension: str, for_external: bool = True)
     return f"{file_preview_url}?timestamp={timestamp}&nonce={nonce}&sign={encoded_sign}"
 
 
-def sign_upload_file(upload_file_id: str, extension: str) -> str:
+def sign_upload_file(upload_file_id: str, extension: str, for_external: bool = True) -> str:
     """
     sign file to get a temporary url for plugin access
     """
     # Use internal URL for plugin/tool file access in Docker environments
-    base_url = dify_config.INTERNAL_FILES_URL or dify_config.FILES_URL
+    base_url = dify_config.FILES_URL if for_external else (dify_config.INTERNAL_FILES_URL or dify_config.FILES_URL)
     file_preview_url = f"{base_url}/files/{upload_file_id}/image-preview"
 
     timestamp = str(int(time.time()))