diff --git a/python/fixup_generated_files.py b/python/fixup_generated_files.py
index 58db7c98b7d5..8fa91aa919bf 100644
--- a/python/fixup_generated_files.py
+++ b/python/fixup_generated_files.py
@@ -24,12 +24,12 @@
 
 def main():
     for file in files:
-        with open(file, "r") as f:
+        with open(file, "r", encoding="utf-8") as f:
             content = f.read()
 
         print("Fixing imports in file:", file)
         for old, new in substitutions.items():
             content = content.replace(old, new)
 
-        with open(file, "w") as f:
+        with open(file, "w", encoding="utf-8") as f:
             f.write(content)
diff --git a/python/packages/autogen-ext/src/autogen_ext/code_executors/azure/_azure_container_code_executor.py b/python/packages/autogen-ext/src/autogen_ext/code_executors/azure/_azure_container_code_executor.py
index 17c4b16a2c15..b7cc7cfde6ac 100644
--- a/python/packages/autogen-ext/src/autogen_ext/code_executors/azure/_azure_container_code_executor.py
+++ b/python/packages/autogen-ext/src/autogen_ext/code_executors/azure/_azure_container_code_executor.py
@@ -250,7 +250,7 @@ async def _setup_functions(self, cancellation_token: CancellationToken) -> None:
                     raise ValueError(f"Packages unavailable in environment: {missing_pkgs}")
 
         func_file = self.work_dir / f"{self._functions_module}.py"
-        func_file.write_text(self._func_code)
+        func_file.write_text(self._func_code, encoding="utf-8")
 
         # Attempt to load the function file to check for syntax errors, imports etc.
         exec_result = await self._execute_code_dont_check_setup(
diff --git a/python/packages/autogen-ext/src/autogen_ext/code_executors/docker/_docker_code_executor.py b/python/packages/autogen-ext/src/autogen_ext/code_executors/docker/_docker_code_executor.py
index 701658572141..8fc26a112094 100644
--- a/python/packages/autogen-ext/src/autogen_ext/code_executors/docker/_docker_code_executor.py
+++ b/python/packages/autogen-ext/src/autogen_ext/code_executors/docker/_docker_code_executor.py
@@ -254,7 +254,7 @@ def timeout(self) -> int:
     async def _setup_functions(self, cancellation_token: CancellationToken) -> None:
         func_file_content = build_python_functions_file(self._functions)
         func_file = self.work_dir / f"{self._functions_module}.py"
-        func_file.write_text(func_file_content)
+        func_file.write_text(func_file_content, encoding="utf-8")
 
         # Collect requirements
         lists_of_packages = [x.python_packages for x in self._functions if isinstance(x, FunctionWithRequirements)]
diff --git a/python/packages/autogen-ext/src/autogen_ext/code_executors/docker_jupyter/_docker_jupyter.py b/python/packages/autogen-ext/src/autogen_ext/code_executors/docker_jupyter/_docker_jupyter.py
index a7dbccc43381..4ac5c3f19518 100644
--- a/python/packages/autogen-ext/src/autogen_ext/code_executors/docker_jupyter/_docker_jupyter.py
+++ b/python/packages/autogen-ext/src/autogen_ext/code_executors/docker_jupyter/_docker_jupyter.py
@@ -275,7 +275,7 @@ def _save_html(self, html_data: str) -> str:
         """Save html data to a file."""
         filename = f"{uuid.uuid4().hex}.html"
         path = os.path.join(str(self._output_dir), filename)
-        with open(path, "w") as f:
+        with open(path, "w", encoding="utf-8") as f:
             f.write(html_data)
         return os.path.abspath(path)
 
diff --git a/python/packages/autogen-ext/src/autogen_ext/code_executors/jupyter/_jupyter_code_executor.py b/python/packages/autogen-ext/src/autogen_ext/code_executors/jupyter/_jupyter_code_executor.py
index 2476b5a3349f..95e95a71ad3a 100644
--- a/python/packages/autogen-ext/src/autogen_ext/code_executors/jupyter/_jupyter_code_executor.py
+++ b/python/packages/autogen-ext/src/autogen_ext/code_executors/jupyter/_jupyter_code_executor.py
@@ -262,7 +262,7 @@ def _save_image(self, image_data_base64: str) -> Path:
     def _save_html(self, html_data: str) -> Path:
         """Save HTML data to a file."""
         path = self._output_dir / f"{uuid.uuid4().hex}.html"
-        path.write_text(html_data)
+        path.write_text(html_data, encoding="utf-8")
         return path.absolute()
 
     async def restart(self) -> None:
diff --git a/python/packages/autogen-ext/src/autogen_ext/code_executors/local/__init__.py b/python/packages/autogen-ext/src/autogen_ext/code_executors/local/__init__.py
index f21d9fe4b8ef..14f78374830e 100644
--- a/python/packages/autogen-ext/src/autogen_ext/code_executors/local/__init__.py
+++ b/python/packages/autogen-ext/src/autogen_ext/code_executors/local/__init__.py
@@ -273,7 +273,7 @@ def cleanup_temp_files(self) -> bool:
     async def _setup_functions(self, cancellation_token: CancellationToken) -> None:
         func_file_content = build_python_functions_file(self._functions)
         func_file = self.work_dir / f"{self._functions_module}.py"
-        func_file.write_text(func_file_content)
+        func_file.write_text(func_file_content, encoding="utf-8")
 
         # Collect requirements
         lists_of_packages = [x.python_packages for x in self._functions if isinstance(x, FunctionWithRequirements)]
diff --git a/python/packages/autogen-ext/src/autogen_ext/experimental/task_centric_memory/utils/chat_completion_client_recorder.py b/python/packages/autogen-ext/src/autogen_ext/experimental/task_centric_memory/utils/chat_completion_client_recorder.py
index 8b981312f427..66c304a6ae05 100644
--- a/python/packages/autogen-ext/src/autogen_ext/experimental/task_centric_memory/utils/chat_completion_client_recorder.py
+++ b/python/packages/autogen-ext/src/autogen_ext/experimental/task_centric_memory/utils/chat_completion_client_recorder.py
@@ -73,7 +73,7 @@ def __init__(
             # Load the previously recorded messages and responses from disk.
             self.logger.info("Replay mode enabled.\nRetrieving session from: " + self.session_file_path)
             try:
-                with open(self.session_file_path, "r") as f:
+                with open(self.session_file_path, "r", encoding="utf-8") as f:
                     self.records = json.load(f)
             except Exception as e:
                 error_str = f"\nFailed to load recorded session: '{self.session_file_path}': {e}"
@@ -211,7 +211,7 @@ def finalize(self) -> None:
                 # Create the directory if it doesn't exist.
                 os.makedirs(os.path.dirname(self.session_file_path), exist_ok=True)
                 # Write the records to disk.
-                with open(self.session_file_path, "w") as f:
+                with open(self.session_file_path, "w", encoding="utf-8") as f:
                     json.dump(self.records, f, indent=2)
                     self.logger.info("\nRecorded session was saved to: " + self.session_file_path)
             except Exception as e:
diff --git a/python/packages/autogen-ext/src/autogen_ext/experimental/task_centric_memory/utils/page_logger.py b/python/packages/autogen-ext/src/autogen_ext/experimental/task_centric_memory/utils/page_logger.py
index fa7fe2f1d567..2ccec94d42cc 100644
--- a/python/packages/autogen-ext/src/autogen_ext/experimental/task_centric_memory/utils/page_logger.py
+++ b/python/packages/autogen-ext/src/autogen_ext/experimental/task_centric_memory/utils/page_logger.py
@@ -117,7 +117,7 @@ def finalize(self) -> None:
         # Write the hash and other details to a file.
         hash_str, num_files, num_subdirs = hash_directory(self.log_dir)
         hash_path = os.path.join(self.log_dir, "hash.txt")
-        with open(hash_path, "w") as f:
+        with open(hash_path, "w", encoding="utf-8") as f:
             f.write(hash_str)
             f.write("\n")
             f.write("{} files\n".format(num_files))
@@ -386,7 +386,7 @@ def flush(self, finished: bool = False) -> None:
             return
         # Create a call tree of the log.
         call_tree_path = os.path.join(self.log_dir, self.name + ".html")
-        with open(call_tree_path, "w") as f:
+        with open(call_tree_path, "w", encoding="utf-8") as f:
             f.write(_html_opening("0 Call Tree", finished=finished))
             f.write(f"<h3>{self.name}</h3>")
             f.write("\n")
@@ -498,7 +498,7 @@ def flush(self) -> None:
         Writes the HTML page to disk.
         """
         page_path = os.path.join(self.page_logger.log_dir, self.index_str + ".html")
-        with open(page_path, "w") as f:
+        with open(page_path, "w", encoding="utf-8") as f:
             f.write(_html_opening(self.file_title, finished=self.finished))
             f.write(f"<h3>{self.file_title}</h3>\n")
             for line in self.lines: