diff --git a/backend/open_webui/retrieval/utils.py b/backend/open_webui/retrieval/utils.py
index b1aec78656..14a64fed60 100644
--- a/backend/open_webui/retrieval/utils.py
+++ b/backend/open_webui/retrieval/utils.py
@@ -566,6 +566,13 @@ async def query_collection(
             log.exception(f'Error when querying the collection: {e}')
             return None, e
 
+    # Sanitize: filter out None/empty queries to prevent embedding crashes
+    # (e.g. when get_last_user_message returns None)
+    queries = [q for q in queries if q]
+    if not queries:
+        log.warning('query_collection: all queries were None or empty, returning empty results')
+        return {'distances': [[]], 'documents': [[]], 'metadatas': [[]]}
+
     # Generate all query embeddings (in one call)
     query_embeddings = await embedding_function(queries, prefix=RAG_EMBEDDING_QUERY_PREFIX)
     log.debug(f'query_collection: processing {len(queries)} queries across {len(collection_names)} collections')
diff --git a/backend/open_webui/tools/builtin.py b/backend/open_webui/tools/builtin.py
index 25d6a2cecb..33d6bfa91e 100644
--- a/backend/open_webui/tools/builtin.py
+++ b/backend/open_webui/tools/builtin.py
@@ -238,9 +238,13 @@ async def fetch_url(
         content, _ = await asyncio.to_thread(get_content_from_url, __request__, url)
 
         # Truncate if configured (WEB_FETCH_MAX_CONTENT_LENGTH)
-        max_length = getattr(__request__.app.state.config, 'WEB_FETCH_MAX_CONTENT_LENGTH', None)
-        if max_length and max_length > 0 and len(content) > max_length:
-            content = content[:max_length] + '\n\n[Content truncated...]'
+        # Guard: content may be None if the web loader silently failed
+        if content is not None:
+            max_length = getattr(__request__.app.state.config, 'WEB_FETCH_MAX_CONTENT_LENGTH', None)
+            if max_length and max_length > 0 and len(content) > max_length:
+                content = content[:max_length] + '\n\n[Content truncated...]'
+        else:
+            content = ''
 
         return content
     except Exception as e:
diff --git a/backend/open_webui/utils/middleware.py b/backend/open_webui/utils/middleware.py
index 3fd4d011df..ab2ca104f4 100644
--- a/backend/open_webui/utils/middleware.py
+++ b/backend/open_webui/utils/middleware.py
@@ -1546,11 +1546,11 @@ async def chat_web_search_handler(request: Request, form_data: dict, extra_param
 
     except Exception as e:
         log.exception(e)
-        queries = [user_message]
+        queries = [user_message or '']
 
     # Check if generated queries are empty
     if len(queries) == 1 and queries[0].strip() == '':
-        queries = [user_message]
+        queries = [user_message or '']
 
     # Check if queries are not found
     if len(queries) == 0:
@@ -1991,7 +1991,7 @@ async def chat_completion_files_handler(
             )
 
         if len(queries) == 0:
-            queries = [get_last_user_message(body['messages'])]
+            queries = [get_last_user_message(body['messages']) or '']
 
         try:
             # Directly await async get_sources_from_items (no thread needed - fully async now)