diff --git a/src/twisted/internet/defer.py b/src/twisted/internet/defer.py
diff --git a/src/twisted/internet/interfaces.py b/src/twisted/internet/interfaces.py
@@ -48,7 +48,7 @@
         ServerFactory,
     )
     from twisted.internet.ssl import ClientContextFactory
-    from twisted.names.dns import Query
+    from twisted.names.dns import Query, RRHeader
     from twisted.protocols.tls import TLSMemoryBIOProtocol
 
     from twisted.python.runtime import platform
@@ -104,7 +104,7 @@ def getDestination() -> IAddress:
 
 
 class IResolverSimple(Interface):
-    def getHostByName(name: str, timeout: Sequence[int]) -> "Deferred":
+    def getHostByName(name: str, timeout: Sequence[int]) -> "Deferred[str]":
         """
         Resolve the domain name C{name} into an IP address.
 
@@ -221,7 +221,9 @@ def resolveHostName(
 
 
 class IResolver(IResolverSimple):
-    def query(query: "Query", timeout: Sequence[int]) -> "Deferred":
+    def query(
+        query: "Query", timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Dispatch C{query} to the method which can handle its type.
 
@@ -239,7 +241,9 @@ def query(query: "Query", timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupAddress(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupAddress(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an A record lookup.
 
@@ -256,7 +260,9 @@ def lookupAddress(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupAddress6(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupAddress6(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an A6 record lookup.
 
@@ -273,7 +279,9 @@ def lookupAddress6(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupIPV6Address(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupIPV6Address(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an AAAA record lookup.
 
@@ -290,7 +298,9 @@ def lookupIPV6Address(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupMailExchange(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupMailExchange(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an MX record lookup.
 
@@ -307,7 +317,9 @@ def lookupMailExchange(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupNameservers(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupNameservers(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an NS record lookup.
 
@@ -324,7 +336,9 @@ def lookupNameservers(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupCanonicalName(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupCanonicalName(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform a CNAME record lookup.
 
@@ -341,7 +355,9 @@ def lookupCanonicalName(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupMailBox(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupMailBox(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an MB record lookup.
 
@@ -358,7 +374,9 @@ def lookupMailBox(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupMailGroup(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupMailGroup(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an MG record lookup.
 
@@ -375,7 +393,9 @@ def lookupMailGroup(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupMailRename(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupMailRename(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an MR record lookup.
 
@@ -392,7 +412,9 @@ def lookupMailRename(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupPointer(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupPointer(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform a PTR record lookup.
 
@@ -409,7 +431,9 @@ def lookupPointer(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupAuthority(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupAuthority(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an SOA record lookup.
 
@@ -426,7 +450,9 @@ def lookupAuthority(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupNull(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupNull(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform a NULL record lookup.
 
@@ -443,7 +469,9 @@ def lookupNull(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupWellKnownServices(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupWellKnownServices(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform a WKS record lookup.
 
@@ -460,7 +488,9 @@ def lookupWellKnownServices(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupHostInfo(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupHostInfo(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform a HINFO record lookup.
 
@@ -477,7 +507,9 @@ def lookupHostInfo(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupMailboxInfo(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupMailboxInfo(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an MINFO record lookup.
 
@@ -494,7 +526,9 @@ def lookupMailboxInfo(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupText(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupText(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform a TXT record lookup.
 
@@ -511,7 +545,9 @@ def lookupText(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupResponsibility(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupResponsibility(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an RP record lookup.
 
@@ -528,7 +564,9 @@ def lookupResponsibility(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupAFSDatabase(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupAFSDatabase(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an AFSDB record lookup.
 
@@ -545,7 +583,9 @@ def lookupAFSDatabase(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupService(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupService(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an SRV record lookup.
 
@@ -562,7 +602,9 @@ def lookupService(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupAllRecords(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupAllRecords(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an ALL_RECORD lookup.
 
@@ -579,7 +621,9 @@ def lookupAllRecords(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupSenderPolicy(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupSenderPolicy(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform a SPF record lookup.
 
@@ -596,7 +640,9 @@ def lookupSenderPolicy(name: str, timeout: Sequence[int]) -> "Deferred":
             C{NotImplementedError}.
         """
 
-    def lookupNamingAuthorityPointer(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupNamingAuthorityPointer(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform a NAPTR record lookup.
 
@@ -613,7 +659,9 @@ def lookupNamingAuthorityPointer(name: str, timeout: Sequence[int]) -> "Deferred
             C{NotImplementedError}.
         """
 
-    def lookupZone(name: str, timeout: Sequence[int]) -> "Deferred":
+    def lookupZone(
+        name: str, timeout: Sequence[int]
+    ) -> "Deferred[Tuple[RRHeader, RRHeader, RRHeader]]":
         """
         Perform an AXFR record lookup.
 
@@ -1287,7 +1335,7 @@ class IReactorCore(Interface):
         "I{during shutdown} and C{False} the rest of the time."
     )
 
-    def resolve(name: str, timeout: Sequence[int]) -> "Deferred":
+    def resolve(name: str, timeout: Sequence[int]) -> "Deferred[str]":
         """
         Return a L{twisted.internet.defer.Deferred} that will resolve
         a hostname.
@@ -2559,15 +2607,15 @@ def setTTL(ttl: int) -> None:
         Set time to live on multicast packets.
         """
 
-    def joinGroup(addr: str, interface: str) -> "Deferred":
+    def joinGroup(addr: str, interface: str) -> "Deferred[None]":
         """
         Join a multicast group. Returns L{Deferred} of success or failure.
 
         If an error occurs, the returned L{Deferred} will fail with
         L{error.MulticastJoinError}.
         """
 
-    def leaveGroup(addr: str, interface: str) -> "Deferred":
+    def leaveGroup(addr: str, interface: str) -> "Deferred[None]":
         """
         Leave multicast group, return L{Deferred} of success.
         """
@@ -2581,7 +2629,7 @@ class IStreamClientEndpoint(Interface):
     @since: 10.1
     """
 
-    def connect(protocolFactory: IProtocolFactory) -> "Deferred":
+    def connect(protocolFactory: IProtocolFactory) -> "Deferred[IProtocol]":
         """
         Connect the C{protocolFactory} to the location specified by this
         L{IStreamClientEndpoint} provider.
@@ -2602,7 +2650,7 @@ class IStreamServerEndpoint(Interface):
     @since: 10.1
     """
 
-    def listen(protocolFactory: IProtocolFactory) -> "Deferred":
+    def listen(protocolFactory: IProtocolFactory) -> "Deferred[IListeningPort]":
         """
         Listen with C{protocolFactory} at the location specified by this
         L{IStreamServerEndpoint} provider.

diff --git a/src/twisted/newsfragments/11017.misc b/src/twisted/newsfragments/11017.misc
diff --git a/src/twisted/newsfragments/9816.misc b/src/twisted/newsfragments/9816.misc
diff --git a/src/twisted/persisted/crefutil.py b/src/twisted/persisted/crefutil.py
@@ -132,7 +132,7 @@ def __init__(self, id):
 from twisted.internet.defer import Deferred
 
 
-class _Defer(Deferred, NotKnown):
+class _Defer(Deferred[object], NotKnown):
     def __init__(self):
         Deferred.__init__(self)
         NotKnown.__init__(self)

diff --git a/src/twisted/python/compat.py b/src/twisted/python/compat.py
@@ -37,7 +37,7 @@
 from io import StringIO as NativeStringIO
 from io import TextIOBase
 from sys import intern
-from types import MethodType as _MethodType
+from types import FrameType, MethodType as _MethodType
 from typing import Any, AnyStr, cast
 from urllib.parse import quote as urlquote
 from urllib.parse import unquote as urlunquote
@@ -187,22 +187,21 @@ def items(d):
     return list(d.items())
 
 
-def currentframe(n=0):
+def currentframe(n: int = 0) -> FrameType:
     """
     In Python 3, L{inspect.currentframe} does not take a stack-level argument.
     Restore that functionality from Python 2 so we don't have to re-implement
     the C{f_back}-walking loop in places where it's called.
 
     @param n: The number of stack levels above the caller to walk.
-    @type n: L{int}
 
     @return: a frame, n levels up the stack from the caller.
-    @rtype: L{types.FrameType}
     """
     f = inspect.currentframe()
     for x in range(n + 1):
         assert f is not None
         f = f.f_back
+    assert f is not None
     return f
 
 
@@ -225,14 +224,16 @@ def execfile(filename, globals, locals=None):
     exec(code, globals, locals)
 
 
-def cmp(a, b):
+# type note: Can't find a Comparable type, despite
+# https://github.com/python/typing/issues/59
+def cmp(a: object, b: object) -> int:
     """
     Compare two objects.
 
     Returns a negative number if C{a < b}, zero if they are equal, and a
     positive number if C{a > b}.
     """
-    if a < b:
+    if a < b:  # type: ignore[operator]
         return -1
     elif a == b:
         return 0
@@ -500,7 +501,7 @@ def _constructMethod(cls, name, self):
     @type self: any object
 
     @return: a bound method
-    @rtype: L{types.MethodType}
+    @rtype: L{_MethodType}
     """
     func = cls.__dict__[name]
     return _MethodType(func, self)

diff --git a/src/twisted/test/test_defer.py b/src/twisted/test/test_defer.py
@@ -176,6 +176,44 @@ def testTwoCallbacks(self):
         self.assertEqual(self.callbackResults, (("hello",), {}))
         self.assertEqual(self.callback2Results, (("hello",), {}))
 
+    def test_addCallbacksNoneErrback(self):
+        """
+        If given None for an errback, addCallbacks uses a pass-through.
+        """
+        error = GenericError("oopsie")
+        deferred = defer.Deferred()
+        deferred.addCallbacks(self._callback, None)
+        deferred.errback(error)
+        deferred.addErrback(self._errback)
+        self.assertIsNone(self.callbackResults)
+        self.assertEqual(len(self.errbackResults[0]), 1)
+        self.assertEqual(self.errbackResults[0][0].value, error)
+        self.assertEqual(self.errbackResults[1], {})
+
+    def test_addCallbacksNoneCallbackArgs(self):
+        """
+        If given None as a callback args and kwargs, () and {} are used.
+        """
+        deferred = defer.Deferred()
+        deferred.addCallbacks(self._callback, self._errback, None, None, (), {})
+        deferred.callback("hello")
+        self.assertIsNone(self.errbackResults)
+        self.assertEqual(self.callbackResults, (("hello",), {}))
+
+    def test_addCallbacksNoneErrbackArgs(self):
+        """
+        If given None as a errback args and kwargs, () and {} are used.
+        """
+        error = GenericError("oopsie")
+        deferred = defer.Deferred()
+        deferred.addCallbacks(self._callback, self._errback, (), {}, None, None)
+        deferred.errback(error)
+        deferred.addErrback(self._errback)
+        self.assertIsNone(self.callbackResults)
+        self.assertEqual(len(self.errbackResults[0]), 1)
+        self.assertEqual(self.errbackResults[0][0].value, error)
+        self.assertEqual(self.errbackResults[1], {})
+
     def testDeferredList(self):
         defr1 = defer.Deferred()
         defr2 = defer.Deferred()