diff --git a/src/fastmcp/server/middleware/error_handling.py b/src/fastmcp/server/middleware/error_handling.py
index 5b235e804..122642250 100644
--- a/src/fastmcp/server/middleware/error_handling.py
+++ b/src/fastmcp/server/middleware/error_handling.py
@@ -89,7 +89,7 @@ class ErrorHandlingMiddleware(Middleware):
             return error
 
         # Map common exceptions to appropriate MCP error codes
-        error_type = type(error.__cause__) if error.__cause__ else type(error)
+        error_type = type(error)
 
         if error_type in (ValueError, TypeError):
             return McpError(