diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 01c70417..41ec546a 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -16,13 +16,10 @@ jobs:
       fail-fast: false
       matrix:
         env:
-          # Werror is not enabled on humble and iron because of gtest
           - ROS_DISTRO: rolling
             ROS_REPO: testing
-            CMAKE_ARGS: -DCMAKE_CXX_FLAGS=-Werror
           - ROS_DISTRO: rolling
             ROS_REPO: main
-            CMAKE_ARGS: -DCMAKE_CXX_FLAGS=-Werror
           - ROS_DISTRO: iron
             ROS_REPO: testing
           - ROS_DISTRO: iron
diff --git a/generate_parameter_library_py/generate_parameter_library_py/cpp_convertions.py b/generate_parameter_library_py/generate_parameter_library_py/cpp_convertions.py
index 01cf6197..c1fa76da 100644
--- a/generate_parameter_library_py/generate_parameter_library_py/cpp_convertions.py
+++ b/generate_parameter_library_py/generate_parameter_library_py/cpp_convertions.py
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-from typing import List, Optional
+from typing import List, Union
 from jinja2 import Template
 from typeguard import typechecked
 import os
@@ -108,18 +108,18 @@ def update_parameter_pass_validation(self) -> str:
         return ''
 
     @typechecked
-    def no_code(self, s: Optional[str]):
+    def no_code(self, s: Union[None, str]):
         return ''
 
     # value to c++ string conversion functions
     @typechecked
-    def bool_to_str(self, cond: Optional[bool]):
+    def bool_to_str(self, cond: Union[None, bool]):
         if cond is None:
             return ''
         return 'true' if cond else 'false'
 
     @typechecked
-    def float_to_str(self, num: Optional[float]):
+    def float_to_str(self, num: Union[None, float]):
         if num is None:
             return ''
         str_num = str(num)
@@ -136,65 +136,65 @@ def float_to_str(self, num: Optional[float]):
         return str_num
 
     @typechecked
-    def int_to_str(self, num: Optional[int]):
+    def int_to_str(self, num: Union[None, int]):
         if num is None:
             return ''
         return str(num)
 
     @typechecked
-    def str_to_str(self, s: Optional[str]):
+    def str_to_str(self, s: Union[None, str]):
         if s is None:
             return ''
         return f'"{s}"'
 
     @typechecked
-    def bool_array_to_str(self, values: Optional[list]):
+    def bool_array_to_str(self, values: Union[None, list]):
         if values is None:
             return ''
         return '{' + ', '.join(self.bool_to_str(x) for x in values) + '}'
 
     @typechecked
-    def float_array_to_str(self, values: Optional[list]):
+    def float_array_to_str(self, values: Union[None, list]):
         if values is None:
             return ''
         return '{' + ', '.join(self.float_to_str(x) for x in values) + '}'
 
     @typechecked
-    def int_array_to_str(self, values: Optional[list]):
+    def int_array_to_str(self, values: Union[None, list]):
         if values is None:
             return ''
         return '{' + ', '.join(self.int_to_str(x) for x in values) + '}'
 
     @typechecked
-    def str_array_to_str(self, s: Optional[list]):
+    def str_array_to_str(self, s: Union[None, list]):
         if s is None:
             return ''
         return '{' + ', '.join(self.str_to_str(x) for x in s) + '}'
 
     @typechecked
-    def str_array_fixed_to_str(self, s: Optional[list]):
+    def str_array_fixed_to_str(self, s: Union[None, list]):
         raise compile_error('not implemented')
 
     @typechecked
-    def str_fixed_to_str(self, s: Optional[str]):
+    def str_fixed_to_str(self, s: Union[None, str]):
         if s is None:
             return ''
         return '{%s}' % self.str_to_str(s)
 
     @typechecked
-    def float_array_fixed_to_str(self, values: Optional[list]):
+    def float_array_fixed_to_str(self, values: Union[None, list]):
         if values is None:
             return ''
         return '{{' + ', '.join(self.float_to_str(x) for x in values) + '}}'
 
     @typechecked
-    def int_array_fixed_to_str(self, values: Optional[list]):
+    def int_array_fixed_to_str(self, values: Union[None, list]):
         if values is None:
             return ''
         return '{{' + ', '.join(self.int_to_str(x) for x in values) + '}}'
 
     @typechecked
-    def bool_array_fixed_to_str(self, values: Optional[list]):
+    def bool_array_fixed_to_str(self, values: Union[None, list]):
         if values is None:
             return ''
         return '{{' + ', '.join(self.bool_to_str(x) for x in values) + '}}'
diff --git a/generate_parameter_library_py/generate_parameter_library_py/parse_yaml.py b/generate_parameter_library_py/generate_parameter_library_py/parse_yaml.py
index 1e8e7f48..7bb1fec6 100644
--- a/generate_parameter_library_py/generate_parameter_library_py/parse_yaml.py
+++ b/generate_parameter_library_py/generate_parameter_library_py/parse_yaml.py
@@ -31,7 +31,15 @@
 
 from jinja2 import Template, Environment
 from typeguard import typechecked
-from typing import Any, List, Optional
+
+# try to import TypeCheckError from typeguard. This was breaking and replaced TypeError in 3.0.0
+try:
+    from typeguard import TypeCheckError
+except ImportError as e:
+    # otherwise, use the old TypeError
+    TypeCheckError = TypeError
+
+from typing import Any, List, Union
 from yaml.parser import ParserError
 from yaml.scanner import ScannerError
 import os
@@ -190,7 +198,7 @@ def __init__(
         func = self.conversation.lang_str_value_func[self.defined_type]
         try:
             self.lang_str_value = func(default_value)
-        except TypeError:
+        except TypeCheckError:
             raise compile_error(
                 f'Parameter {param_name} has incorrect type. Expected: {defined_type}, got: {self.get_yaml_type_from_python(default_value)}'
             )
@@ -314,7 +322,7 @@ class ValidationFunction:
     def __init__(
         self,
         function_name: str,
-        arguments: Optional[List[Any]],
+        arguments: Union[None, List[Any]],
         code_gen_variable: CodeGenVariableBase,
     ):
         self.code_gen_variable = code_gen_variable
diff --git a/generate_parameter_library_py/generate_parameter_library_py/python_convertions.py b/generate_parameter_library_py/generate_parameter_library_py/python_convertions.py
index c171f6c9..0a09dd0d 100644
--- a/generate_parameter_library_py/generate_parameter_library_py/python_convertions.py
+++ b/generate_parameter_library_py/generate_parameter_library_py/python_convertions.py
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-from typing import List, Optional
+from typing import List, Union
 from jinja2 import Template
 from typeguard import typechecked
 import os
@@ -107,18 +107,18 @@ def update_parameter_pass_validation(self) -> str:
         return ''
 
     @typechecked
-    def no_code(self, s: Optional[str]):
+    def no_code(self, s: Union[None, str]):
         return ''
 
     # value to c++ string conversion functions
     @typechecked
-    def bool_to_str(self, cond: Optional[bool]):
+    def bool_to_str(self, cond: Union[None, bool]):
         if cond is None:
             return ''
         return 'True' if cond else 'False'
 
     @typechecked
-    def float_to_str(self, num: Optional[float]):
+    def float_to_str(self, num: Union[None, float]):
         if num is None:
             return ''
         str_num = str(num)
@@ -135,65 +135,65 @@ def float_to_str(self, num: Optional[float]):
         return str_num
 
     @typechecked
-    def int_to_str(self, num: Optional[int]):
+    def int_to_str(self, num: Union[None, int]):
         if num is None:
             return ''
         return str(num)
 
     @typechecked
-    def str_to_str(self, s: Optional[str]):
+    def str_to_str(self, s: Union[None, str]):
         if s is None:
             return ''
         return f'"{s}"'
 
     @typechecked
-    def bool_array_to_str(self, values: Optional[list]):
+    def bool_array_to_str(self, values: Union[None, list]):
         if values is None:
             return ''
         return '[' + ', '.join(self.bool_to_str(x) for x in values) + ']'
 
     @typechecked
-    def float_array_to_str(self, values: Optional[list]):
+    def float_array_to_str(self, values: Union[None, list]):
         if values is None:
             return ''
         return '[' + ', '.join(self.float_to_str(x) for x in values) + ']'
 
     @typechecked
-    def int_array_to_str(self, values: Optional[list]):
+    def int_array_to_str(self, values: Union[None, list]):
         if values is None:
             return ''
         return '[' + ', '.join(self.int_to_str(x) for x in values) + ']'
 
     @typechecked
-    def str_array_to_str(self, s: Optional[list]):
+    def str_array_to_str(self, s: Union[None, list]):
         if s is None:
             return ''
         return '[' + ', '.join(self.str_to_str(x) for x in s) + ']'
 
     @typechecked
-    def str_array_fixed_to_str(self, s: Optional[list]):
+    def str_array_fixed_to_str(self, s: Union[None, list]):
         raise compile_error('not implemented')
 
     @typechecked
-    def str_fixed_to_str(self, s: Optional[str]):
+    def str_fixed_to_str(self, s: Union[None, str]):
         if s is None:
             return ''
         return '%s' % self.str_to_str(s)
 
     @typechecked
-    def float_array_fixed_to_str(self, values: Optional[list]):
+    def float_array_fixed_to_str(self, values: Union[None, list]):
         if values is None:
             return ''
         return '[' + ', '.join(self.float_to_str(x) for x in values) + ']'
 
     @typechecked
-    def int_array_fixed_to_str(self, values: Optional[list]):
+    def int_array_fixed_to_str(self, values: Union[None, list]):
         if values is None:
             return ''
         return '[' + ', '.join(self.int_to_str(x) for x in values) + ']'
 
     @typechecked
-    def bool_array_fixed_to_str(self, values: Optional[list]):
+    def bool_array_fixed_to_str(self, values: Union[None, list]):
         if values is None:
             return ''
         return '[' + ', '.join(self.bool_to_str(x) for x in values) + ']'