diff --git a/google/genai/_gaos/google_genai.py b/google/genai/_gaos/google_genai.py
index 74efdce224..3490a227eb 100644
--- a/google/genai/_gaos/google_genai.py
+++ b/google/genai/_gaos/google_genai.py
@@ -1279,7 +1279,8 @@ def upload(
             or 'v1alpha'
         ).lstrip('/')
 
-        handshake_res = self._internal.start_upload(
+        handshake_res = wrap_sdk_call(
+            self._internal.start_upload,
             environment=clean_env,
             path=clean_path,
             x_goog_upload_header_content_length=size_bytes,
@@ -1437,7 +1438,8 @@ async def upload(
             or 'v1alpha'
         ).lstrip('/')
 
-        handshake_res = await self._internal.start_upload(
+        handshake_res = await async_wrap_sdk_call(
+            self._internal.start_upload,
             environment=clean_env,
             path=clean_path,
             x_goog_upload_header_content_length=size_bytes,
diff --git a/google/genai/_gaos/lib/compat_errors.py b/google/genai/_gaos/lib/compat_errors.py
index 7bd524927e..a9ef887336 100644
--- a/google/genai/_gaos/lib/compat_errors.py
+++ b/google/genai/_gaos/lib/compat_errors.py
@@ -350,9 +350,8 @@ def after_error(
         response: Optional[httpx.Response],
         error: Optional[Exception],
     ) -> tuple[Optional[httpx.Response], Optional[Exception]]:
-        if error is None:
-            return response, error
-        return response, wrap_sdk_error(error)  # type: ignore[return-value]
+        # Keep httpx errors for retries; wrap_sdk_call translates the final error.
+        return response, error
 
     def after_parse_error(
         self,
diff --git a/google/genai/tests/interactions/test_httpx_compat.py b/google/genai/tests/interactions/test_httpx_compat.py
index ea867f6a04..e42db959f5 100644
--- a/google/genai/tests/interactions/test_httpx_compat.py
+++ b/google/genai/tests/interactions/test_httpx_compat.py
@@ -14,6 +14,8 @@
 
 """Tests for httpx and httpx2 compatibility across the GAOS client."""
 
+from unittest import mock
+
 import httpx
 import pytest
 
@@ -113,6 +115,37 @@ async def failing_agen():
   assert "async stream network broken" in str(exc_info.value)
 
 
+@pytest.mark.parametrize("error_type,api_error_type", [
+    (httpx.ConnectError, compat_errors.APIConnectionError),
+    (httpx.ReadTimeout, compat_errors.APITimeoutError),
+])
+@pytest.mark.parametrize(
+    "operation,method", [("sync", "POST"), ("async", "POST"), ("upload", "PUT")]
+)
+@pytest.mark.asyncio
+async def test_transport_errors(operation, method, error_type, api_error_type):
+  handler = mock.Mock(side_effect=error_type("request failed"))
+  client = client_lib.Client(
+      api_key="fake-key",
+      http_options={
+          "client_args": {"transport": httpx.MockTransport(handler)},
+          "async_client_args": {"transport": httpx.MockTransport(handler)},
+          "retry_options": {"initial_delay": 0, "max_delay": 0},
+      },
+  )
+  with pytest.raises(api_error_type) as exc_info:
+    if operation == "upload":
+      client.environments.files.upload(
+          environment="env_123", path="src/main.py", file=b"print(1)"
+      )
+    elif operation == "async":
+      await client.aio.interactions.create(model="gemini-1.5-flash", input="Hello")
+    else:
+      client.interactions.create(model="gemini-1.5-flash", input="Hello")
+  assert [call.args[0].method for call in handler.call_args_list] == [method] * 4
+  assert isinstance(exc_info.value.__cause__, error_type)
+
+
 # --- httpx2 tests (run in CI when httpx2 is installed) ---