diff --git a/litellm/proxy/common_utils/openapi_schema_compat.py b/litellm/proxy/common_utils/openapi_schema_compat.py
new file mode 100644
index 0000000000..600b3909ec
--- /dev/null
+++ b/litellm/proxy/common_utils/openapi_schema_compat.py
@@ -0,0 +1,106 @@
+"""
+Utility module for handling OpenAPI schema generation compatibility with FastAPI 0.120+.
+
+FastAPI 0.120+ has stricter schema generation that fails on certain types like openai.Timeout.
+This module provides a compatibility layer to handle these cases gracefully.
+"""
+
+from typing import Any, Dict
+
+from litellm._logging import verbose_proxy_logger
+
+
+def get_openapi_schema_with_compat(
+    get_openapi_func,
+    title: str,
+    version: str,
+    description: str,
+    routes: list,
+) -> Dict[str, Any]:
+    """
+    Generate OpenAPI schema with compatibility handling for FastAPI 0.120+.
+    
+    This function patches Pydantic's schema generation to handle non-serializable types
+    like openai.Timeout that cause PydanticSchemaGenerationError in FastAPI 0.120+.
+    
+    Args:
+        get_openapi_func: The FastAPI get_openapi function
+        title: API title
+        version: API version
+        description: API description
+        routes: List of routes
+        
+    Returns:
+        OpenAPI schema dictionary
+    """
+    # FastAPI 0.120+ may fail schema generation for certain types (e.g., openai.Timeout)
+    # Patch Pydantic's schema generation to handle unknown types gracefully
+    try:
+        from pydantic._internal._generate_schema import GenerateSchema
+        from pydantic_core import core_schema
+
+        # Store original method
+        original_unknown_type_schema = GenerateSchema._unknown_type_schema
+        
+        def patched_unknown_type_schema(self, obj):
+            """Patch to handle openai.Timeout and other non-serializable types"""
+            # Check if it's openai.Timeout or similar types
+            obj_str = str(obj)
+            obj_module = getattr(obj, '__module__', '')
+            
+            if (obj_module == 'openai' and 'Timeout' in obj_str) or \
+               (hasattr(obj, '__name__') and obj.__name__ == 'Timeout' and obj_module == 'openai'):
+                # Return a simple string schema for Timeout types
+                return core_schema.str_schema()
+            
+            # For other unknown types, try to return a default schema
+            # This prevents the error from propagating
+            try:
+                return core_schema.any_schema()
+            except Exception:
+                # Last resort: return string schema
+                return core_schema.str_schema()
+        
+        # Apply patch
+        GenerateSchema._unknown_type_schema = patched_unknown_type_schema
+        
+        try:
+            openapi_schema = get_openapi_func(
+                title=title,
+                version=version,
+                description=description,
+                routes=routes,
+            )
+        finally:
+            # Restore original method
+            GenerateSchema._unknown_type_schema = original_unknown_type_schema
+            
+        return openapi_schema
+            
+    except (ImportError, AttributeError) as e:
+        # If patching fails, try normal generation with error handling
+        verbose_proxy_logger.debug(f"Could not patch Pydantic schema generation: {e}. Trying normal generation.")
+        try:
+            return get_openapi_func(
+                title=title,
+                version=version,
+                description=description,
+                routes=routes,
+            )
+        except Exception as pydantic_error:
+            # Check if it's a PydanticSchemaGenerationError by checking the error type name
+            # This avoids import issues if PydanticSchemaGenerationError is not available
+            error_type_name = type(pydantic_error).__name__
+            if error_type_name == "PydanticSchemaGenerationError" or "PydanticSchemaGenerationError" in str(type(pydantic_error)):
+                # If we still get the error, log it and return minimal schema
+                verbose_proxy_logger.warning(f"PydanticSchemaGenerationError during schema generation: {pydantic_error}")
+                return {
+                    "openapi": "3.0.0",
+                    "info": {"title": title, "version": version, "description": description or ""},
+                    "paths": {},
+                    "components": {"schemas": {}},
+                }
+            else:
+                # Re-raise if it's a different error
+                raise
+
diff --git a/litellm/proxy/proxy_server.py b/litellm/proxy/proxy_server.py
index 3e9ce39a08..dd88fce830 100644
--- a/litellm/proxy/proxy_server.py
+++ b/litellm/proxy/proxy_server.py
@@ -774,7 +774,13 @@ def get_openapi_schema():
     if app.openapi_schema:
         return app.openapi_schema
 
-    openapi_schema = get_openapi(
+    # Use compatibility wrapper for FastAPI 0.120+ schema generation
+    from litellm.proxy.common_utils.openapi_schema_compat import (
+        get_openapi_schema_with_compat,
+    )
+
+    openapi_schema = get_openapi_schema_with_compat(
+        get_openapi_func=get_openapi,
         title=app.title,
         version=app.version,
         description=app.description,
@@ -793,18 +799,25 @@ def get_openapi_schema():
 
         # Extract parameters from the route
         parameters = []
-        if hasattr(route, "dependant"):
-            for param in route.dependant.query_params:
-                parameters.append(
-                    {
-                        "name": param.name,
-                        "in": "query",
-                        "required": param.required,
-                        "schema": {
-                            "type": "string"
-                        },  # You can make this more specific if needed
-                    }
-                )
+        try:
+            if hasattr(route, "dependant") and route.dependant is not None:
+                # Handle both FastAPI <0.120 and >=0.120
+                query_params = getattr(route.dependant, "query_params", [])
+                if query_params:
+                    for param in query_params:
+                        parameters.append(
+                            {
+                                "name": param.name,
+                                "in": "query",
+                                "required": param.required,
+                                "schema": {
+                                    "type": "string"
+                                },  # You can make this more specific if needed
+                            }
+                        )
+        except (AttributeError, TypeError):
+            # If we can't access query_params, continue without them
+            pass
 
         openapi_schema["paths"][base_path] = {
             "get": {