From cdddab056c88788034f0e0e96259902826233db6 Mon Sep 17 00:00:00 2001
From: Lianmin Zheng <lianminzheng@gmail.com>
Date: Fri, 12 Sep 2025 17:46:56 -0700
Subject: [PATCH] [Auto Sync] Update xgrammar_backend.py (20250913) (#10395)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
---
 python/sglang/srt/constrained/xgrammar_backend.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/python/sglang/srt/constrained/xgrammar_backend.py b/python/sglang/srt/constrained/xgrammar_backend.py
index 8ff55d261..3f21e854b 100644
--- a/python/sglang/srt/constrained/xgrammar_backend.py
+++ b/python/sglang/srt/constrained/xgrammar_backend.py
@@ -173,6 +173,10 @@ class XGrammarGrammarBackend(BaseGrammarBackend):
         if hasattr(tokenizer, "init_xgrammar"):
             # For special tokenizer
             tokenizer_info, override_stop_tokens = tokenizer.init_xgrammar()
+
+            if tokenizer_info is None:
+                # Not supported tokenizer
+                return
         else:
             # Create TokenizerInfo with model's EOS tokens as the authoritative stop tokens
             # This ensures consistency between what the model considers EOS and what XGrammar uses