From 1dcc2610b243ffb76a17f2fb7fd6d716d4ff5699 Mon Sep 17 00:00:00 2001
From: Stuart Reed <stuart.reed@ethereum.org>
Date: Mon, 19 Jun 2023 15:38:30 -0600
Subject: [PATCH] Skip formatting response when None

---
 .../middleware/test_formatting_middleware.py  | 19 ++++++++++++++++++-
 web3/middleware/formatting.py                 |  6 +++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/tests/core/middleware/test_formatting_middleware.py b/tests/core/middleware/test_formatting_middleware.py
index a277339577..8f7f9ca807 100644
--- a/tests/core/middleware/test_formatting_middleware.py
+++ b/tests/core/middleware/test_formatting_middleware.py
@@ -91,6 +91,23 @@ def test_formatting_middleware_result_formatters(w3):
     assert actual == expected
 
 
+def test_formatting_middleware_result_formatters_for_none(w3):
+    w3.middleware_onion.add(
+        construct_result_generator_middleware(
+            {RPCEndpoint("test_endpoint"): lambda method, params: None}
+        )
+    )
+    w3.middleware_onion.add(
+        construct_formatting_middleware(
+            result_formatters={RPCEndpoint("test_endpoint"): lambda x: hex(x)}
+        )
+    )
+
+    expected = None
+    actual = w3.manager.request_blocking("test_endpoint", [])
+    assert actual == expected
+
+
 def test_formatting_middleware_error_formatters(w3):
     w3.middleware_onion.add(
         construct_error_generator_middleware(
@@ -106,4 +123,4 @@ def test_formatting_middleware_error_formatters(w3):
     expected = "error"
     with pytest.raises(ValueError) as err:
         w3.manager.request_blocking("test_endpoint", [])
-    assert str(err.value) == expected
\ No newline at end of file
+    assert str(err.value) == expected
diff --git a/web3/middleware/formatting.py b/web3/middleware/formatting.py
index d6637085d8..c036877850 100644
--- a/web3/middleware/formatting.py
+++ b/web3/middleware/formatting.py
@@ -50,7 +50,11 @@ def _format_response(
             response, response_type, method_response_formatter(appropriate_response)
         )
 
-    if "result" in response and method in result_formatters:
+    if (
+        "result" in response
+        and response["result"] is not None
+        and method in result_formatters
+    ):
         return _format_response("result", result_formatters[method])
     elif "error" in response and method in error_formatters:
         return _format_response("error", error_formatters[method])