diff --git a/.semversioner/next-release/patch-20240711092703710242.json b/.semversioner/next-release/patch-20240711092703710242.json
new file mode 100644
index 00000000..7868b33b
--- /dev/null
+++ b/.semversioner/next-release/patch-20240711092703710242.json
@@ -0,0 +1,4 @@
+{
+  "type": "patch",
+  "description": "support non-open ai model config to prompt tune"
+}
diff --git a/graphrag/index/utils/tokens.py b/graphrag/index/utils/tokens.py
index e308c81f..b0fa435b 100644
--- a/graphrag/index/utils/tokens.py
+++ b/graphrag/index/utils/tokens.py
@@ -2,10 +2,12 @@
 # Licensed under the MIT License
 
 """Utilities for working with tokens."""
+import logging
 
 import tiktoken
 
 DEFAULT_ENCODING_NAME = "cl100k_base"
+log = logging.getLogger(__name__)
 
 
 def num_tokens_from_string(
@@ -13,7 +15,12 @@ def num_tokens_from_string(
 ) -> int:
     """Return the number of tokens in a text string."""
     if model is not None:
-        encoding = tiktoken.encoding_for_model(model)
+        try:
+            encoding = tiktoken.encoding_for_model(model)
+        except KeyError as e:
+            log.error(f"Failed to get encoding for {model} when getting num_tokens_from_string, "
+                      f"fall back to default encoding {DEFAULT_ENCODING_NAME}")
+            encoding = tiktoken.get_encoding(DEFAULT_ENCODING_NAME)
     else:
         encoding = tiktoken.get_encoding(encoding_name or DEFAULT_ENCODING_NAME)
     return len(encoding.encode(string))