diff --git a/pypdf/_protocols.py b/pypdf/_protocols.py
index ba6cd8a3c..c6f2bbebd 100644
--- a/pypdf/_protocols.py
+++ b/pypdf/_protocols.py
@@ -33,7 +33,7 @@ def hash_value(self) -> bytes:
         ...
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         ...
 
diff --git a/pypdf/_writer.py b/pypdf/_writer.py
index 8838f6445..290166b25 100644
--- a/pypdf/_writer.py
+++ b/pypdf/_writer.py
@@ -1181,6 +1181,7 @@ def _write_pdf_structure(self, stream: StreamType) -> List[int]:
         object_positions = []
         stream.write(self.pdf_header + b"\n")
         stream.write(b"%\xE2\xE3\xCF\xD3\n")
+
         for i, obj in enumerate(self._objects):
             obj = self._objects[i]
             # If the obj is None we can't write anything
@@ -1230,7 +1231,7 @@ def _write_trailer(self, stream: StreamType, xref_location: int) -> None:
             trailer[NameObject(TK.ID)] = self._ID
         if hasattr(self, "_encrypt"):
             trailer[NameObject(TK.ENCRYPT)] = self._encrypt
-        trailer.write_to_stream(stream, None)
+        trailer.write_to_stream(stream)
         stream.write(b_(f"\nstartxref\n{xref_location}\n%%EOF\n"))  # eof
 
     def add_metadata(self, infos: Dict[str, Any]) -> None:
diff --git a/pypdf/generic/_base.py b/pypdf/generic/_base.py
index be3d71c45..457e88aca 100644
--- a/pypdf/generic/_base.py
+++ b/pypdf/generic/_base.py
@@ -146,7 +146,7 @@ def getObject(self) -> Optional["PdfObject"]:  # deprecated
         return self.get_object()
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         raise NotImplementedError
 
@@ -164,7 +164,7 @@ def clone(
         )
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         stream.write(b"null")
 
@@ -218,7 +218,7 @@ def __repr__(self) -> str:
         return "True" if self.value else "False"
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         if self.value:
             stream.write(b"true")
@@ -311,7 +311,7 @@ def __ne__(self, other: Any) -> bool:
         return not self.__eq__(other)
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         stream.write(b_(f"{self.idnum} {self.generation} R"))
 
@@ -397,7 +397,7 @@ def as_numeric(self) -> float:
         return float(self)
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         stream.write(self.myrepr().encode("utf8"))
 
@@ -434,7 +434,7 @@ def as_numeric(self) -> int:
         return int(repr(self).encode("utf8"))
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         stream.write(repr(self).encode("utf8"))
 
@@ -488,7 +488,7 @@ def original_bytes(self) -> bytes:
         return self
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         bytearr = self
         if encryption_key:
@@ -556,7 +556,7 @@ def get_original_bytes(self) -> bytes:
             raise Exception("no information about original bytes")
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         # Try to write the string out as a PDFDocEncoding encoded string.  It's
         # nicer to look at in the PDF file.  Sadly, we take a performance hit
@@ -570,7 +570,7 @@ def write_to_stream(
 
             bytearr = RC4_encrypt(encryption_key, bytearr)
             obj = ByteStringObject(bytearr)
-            obj.write_to_stream(stream, None)
+            obj.write_to_stream(stream)
         else:
             stream.write(b"(")
             for c in bytearr:
@@ -615,7 +615,7 @@ def clone(
         )
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         stream.write(self.renumber())  # b_(renumber(self)))
 
diff --git a/pypdf/generic/_data_structures.py b/pypdf/generic/_data_structures.py
index 985424322..2f04d1a74 100644
--- a/pypdf/generic/_data_structures.py
+++ b/pypdf/generic/_data_structures.py
@@ -111,7 +111,7 @@ def items(self) -> Iterable[Any]:
         return enumerate(self)
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         stream.write(b"[")
         for data in self:
@@ -338,7 +338,7 @@ def xmpMetadata(self) -> Optional[PdfObject]:  # deprecated
         return self.xmp_metadata
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         stream.write(b"<<\n")
         for key, value in list(self.items()):
@@ -783,7 +783,7 @@ def _data(self, value: Any) -> None:
         self.__data = value
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         self[NameObject(SA.LENGTH)] = NumberObject(len(self._data))
         DictionaryObject.write_to_stream(self, stream, encryption_key)
@@ -1106,14 +1106,14 @@ def _data(self) -> bytes:
             if operator == b"INLINE IMAGE":
                 new_data.write(b"BI")
                 dict_text = BytesIO()
-                operands["settings"].write_to_stream(dict_text, None)
+                operands["settings"].write_to_stream(dict_text)
                 new_data.write(dict_text.getvalue()[2:-2])
                 new_data.write(b"ID ")
                 new_data.write(operands["data"])
                 new_data.write(b"EI")
             else:
                 for op in operands:
-                    op.write_to_stream(new_data, None)
+                    op.write_to_stream(new_data)
                     new_data.write(b" ")
                 new_data.write(b_(operator))
             new_data.write(b"\n")
@@ -1411,7 +1411,7 @@ def getDestArray(self) -> "ArrayObject":  # deprecated
         return self.dest_array
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         stream.write(b"<<\n")
         key = NameObject("/D")
diff --git a/pypdf/generic/_outline.py b/pypdf/generic/_outline.py
index dcff76d6e..e67ce0242 100644
--- a/pypdf/generic/_outline.py
+++ b/pypdf/generic/_outline.py
@@ -7,7 +7,7 @@
 
 class OutlineItem(Destination):
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         stream.write(b"<<\n")
         for key in [
diff --git a/pypdf/xmp.py b/pypdf/xmp.py
index 23e8ad3f7..d90964113 100644
--- a/pypdf/xmp.py
+++ b/pypdf/xmp.py
@@ -232,7 +232,7 @@ def rdfRoot(self) -> XmlElement:  # deprecated
         return self.rdf_root
 
     def write_to_stream(
-        self, stream: StreamType, encryption_key: Union[None, str, bytes]
+        self, stream: StreamType, encryption_key: Union[None, str, bytes] = None
     ) -> None:
         self.stream.write_to_stream(stream, encryption_key)
 
diff --git a/tests/test_generic.py b/tests/test_generic.py
index dfac41c9a..80ee76b66 100644
--- a/tests/test_generic.py
+++ b/tests/test_generic.py
@@ -86,7 +86,7 @@ def test_boolean_object(value, expected, tell):
 def test_boolean_object_write():
     stream = BytesIO()
     boolobj = BooleanObject(None)
-    boolobj.write_to_stream(stream, encryption_key=None)
+    boolobj.write_to_stream(stream)
     stream.seek(0, 0)
     assert stream.read() == b"false"
 
@@ -213,23 +213,23 @@ def test_name_object(caplog):
 
     # test write
     b = BytesIO()
-    NameObject("/hello").write_to_stream(b, None)
+    NameObject("/hello").write_to_stream(b)
     assert bytes(b.getbuffer()) == b"/hello"
 
     caplog.clear()
     b = BytesIO()
-    NameObject("hello").write_to_stream(b, None)
+    NameObject("hello").write_to_stream(b)
     assert bytes(b.getbuffer()) == b"hello"
     assert "Incorrect first char" in caplog.text
 
     caplog.clear()
     b = BytesIO()
-    NameObject("/DIJMAC+Arial Black#1").write_to_stream(b, None)
+    NameObject("/DIJMAC+Arial Black#1").write_to_stream(b)
     assert bytes(b.getbuffer()) == b"/DIJMAC+Arial#20Black#231"
     assert caplog.text == ""
 
     b = BytesIO()
-    NameObject("/你好世界").write_to_stream(b, None)
+    NameObject("/你好世界").write_to_stream(b)
     assert bytes(b.getbuffer()) == b"/#E4#BD#A0#E5#A5#BD#E4#B8#96#E7#95#8C"
     assert caplog.text == ""
 
@@ -259,7 +259,7 @@ def test_destination_fit_v():
 def test_outline_item_write_to_stream():
     stream = BytesIO()
     oi = OutlineItem(NameObject("title"), NullObject(), Fit.fit_vertically(left=0))
-    oi.write_to_stream(stream, None)
+    oi.write_to_stream(stream)
     stream.seek(0, 0)
     assert stream.read() == b"<<\n/Title (title)\n/Dest [ null /FitV 0.0 ]\n>>"
 
diff --git a/tests/test_protocols.py b/tests/test_protocols.py
index 8c8a6ff50..8ca8167c0 100644
--- a/tests/test_protocols.py
+++ b/tests/test_protocols.py
@@ -12,4 +12,4 @@ def test_pdfobjectprotocol():
     assert o._reference_clone(None, None) is None
     assert o.get_object() is None
     assert o.hash_value() is None
-    assert o.write_to_stream(None, None) is None
+    assert o.write_to_stream(None) is None
diff --git a/tests/test_workflows.py b/tests/test_workflows.py
index 7a9ddcb53..d3eabdbc3 100644
--- a/tests/test_workflows.py
+++ b/tests/test_workflows.py
@@ -904,14 +904,14 @@ def test_extra_test_iss1541():
     cs = ContentStream(reader.pages[0]["/Contents"], None, None)
     cs.operations.insert(-1, ([], b"EMC"))
     bu = BytesIO()
-    cs.write_to_stream(bu, None)
+    cs.write_to_stream(bu)
     bu.seek(0)
     ContentStream(read_object(bu, None, None), None, None).operations
 
     cs = ContentStream(reader.pages[0]["/Contents"], None, None)
     cs.operations.insert(-1, ([], b"E!C"))
     bu = BytesIO()
-    cs.write_to_stream(bu, None)
+    cs.write_to_stream(bu)
     bu.seek(0)
     with pytest.raises(PdfReadError) as exc:
         ContentStream(read_object(bu, None, None), None, None).operations