diff --git a/src/openai/_client.py b/src/openai/_client.py
index ed9b46f4b0..064f22bf6d 100644
--- a/src/openai/_client.py
+++ b/src/openai/_client.py
@@ -147,7 +147,7 @@ def __init__(
         self.websocket_base_url = websocket_base_url
 
         if base_url is None:
-            base_url = os.environ.get("OPENAI_BASE_URL")
+            base_url = os.environ.get("OPENAI_BASE_URL") or None
         if base_url is None:
             base_url = f"https://api.openai.com/v1"
 
@@ -466,7 +466,7 @@ def __init__(
         self.websocket_base_url = websocket_base_url
 
         if base_url is None:
-            base_url = os.environ.get("OPENAI_BASE_URL")
+            base_url = os.environ.get("OPENAI_BASE_URL") or None
         if base_url is None:
             base_url = f"https://api.openai.com/v1"
 
diff --git a/src/openai/_streaming.py b/src/openai/_streaming.py
index f586de74ff..77deae40db 100644
--- a/src/openai/_streaming.py
+++ b/src/openai/_streaming.py
@@ -63,7 +63,7 @@ def __stream__(self) -> Iterator[_T]:
             if sse.event and sse.event.startswith("thread."):
                 data = sse.json()
 
-                if sse.event == "error" and is_mapping(data) and data.get("error"):
+                if sse.event == "error" and is_mapping(data) and (data.get("error") or data.get("message")):
                     message = None
                     error = data.get("error")
                     if is_mapping(error):
@@ -80,7 +80,7 @@ def __stream__(self) -> Iterator[_T]:
                 yield process_data(data={"data": data, "event": sse.event}, cast_to=cast_to, response=response)
             else:
                 data = sse.json()
-                if is_mapping(data) and data.get("error"):
+                if is_mapping(data) and (data.get("error") or data.get("message")):
                     message = None
                     error = data.get("error")
                     if is_mapping(error):
@@ -165,7 +165,7 @@ async def __stream__(self) -> AsyncIterator[_T]:
             if sse.event and sse.event.startswith("thread."):
                 data = sse.json()
 
-                if sse.event == "error" and is_mapping(data) and data.get("error"):
+                if sse.event == "error" and is_mapping(data) and (data.get("error") or data.get("message")):
                     message = None
                     error = data.get("error")
                     if is_mapping(error):
@@ -182,7 +182,7 @@ async def __stream__(self) -> AsyncIterator[_T]:
                 yield process_data(data={"data": data, "event": sse.event}, cast_to=cast_to, response=response)
             else:
                 data = sse.json()
-                if is_mapping(data) and data.get("error"):
+                if is_mapping(data) and (data.get("error") or data.get("message")):
                     message = None
                     error = data.get("error")
                     if is_mapping(error):
diff --git a/src/openai/types/responses/response_text_delta_event.py b/src/openai/types/responses/response_text_delta_event.py
index b5379b7ac3..bc121e5c8d 100644
--- a/src/openai/types/responses/response_text_delta_event.py
+++ b/src/openai/types/responses/response_text_delta_event.py
@@ -37,7 +37,7 @@ class ResponseTextDeltaEvent(BaseModel):
     item_id: str
     """The ID of the output item that the text delta was added to."""
 
-    logprobs: List[Logprob]
+    logprobs: Optional[List[Logprob]] = None
     """The log probabilities of the tokens in the delta."""
 
     output_index: int