fix(chats): fix chat search crash (#18576)

* fix(chats): handle null bytes in PostgreSQL search

Removes null bytes from message content before performing
case-insensitive search in PostgreSQL, preventing conversion
errors and ensuring reliable query results.

* fix(chats): prevent null byte errors in PostgreSQL queries

Ensures chat content and titles containing null bytes are excluded from PostgreSQL text queries to avoid conversion errors.

Improves reliability of search and filtering by handling problematic characters in JSON fields.

backend/open_webui/models/chats.py

@@ -765,15 +765,20 @@ class ChatTable:
                     )
 
             elif dialect_name == "postgresql":
-                # PostgreSQL relies on proper JSON query for search
+                # PostgreSQL doesn't allow null bytes in text. We filter those out by checking
+                # the JSON representation for \u0000 before attempting text extraction
                 postgres_content_sql = (
                     "EXISTS ("
                     "    SELECT 1 "
                     "    FROM json_array_elements(Chat.chat->'messages') AS message "
-                    "    WHERE LOWER(message->>'content') LIKE '%' || :content_key || '%'"
+                    "    WHERE message->'content' IS NOT NULL "
+                    "    AND (message->'content')::text NOT LIKE '%\\u0000%' "
+                    "    AND LOWER(message->>'content') LIKE '%' || :content_key || '%'"
                     ")"
                 )
                 postgres_content_clause = text(postgres_content_sql)
+                # Also filter out chats with null bytes in title
+                query = query.filter(text("Chat.title::text NOT LIKE '%\\x00%'"))
                 query = query.filter(
                     or_(
                         Chat.title.ilike(bindparam("title_key")),