diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index f0ef30e7fc7..6cc3fa13128 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1016,7 +1016,17 @@ class Popen(object):
         def terminate(self):
             """Terminates the process
             """
-            _subprocess.TerminateProcess(self._handle, 1)
+            try:
+                _subprocess.TerminateProcess(self._handle, 1)
+            except OSError as e:
+                # ERROR_ACCESS_DENIED (winerror 5) is received when the
+                # process already died.
+                if e.winerror != 5:
+                    raise
+                rc = _subprocess.GetExitCodeProcess(self._handle)
+                if rc == _subprocess.STILL_ACTIVE:
+                    raise
+                self.returncode = rc
 
         kill = terminate
 
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index b66356ddbf8..20b1ade753d 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -812,6 +812,27 @@ class POSIXProcessTestCase(BaseTestCase):
         getattr(p, method)(*args)
         return p
 
+    def _kill_dead_process(self, method, *args):
+        # Do not inherit file handles from the parent.
+        # It should fix failures on some platforms.
+        p = subprocess.Popen([sys.executable, "-c", """if 1:
+                             import sys, time
+                             sys.stdout.write('x\\n')
+                             sys.stdout.flush()
+                             """],
+                             close_fds=True,
+                             stdin=subprocess.PIPE,
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE)
+        # Wait for the interpreter to be completely initialized before
+        # sending any signal.
+        p.stdout.read(1)
+        # The process should end after this
+        time.sleep(1)
+        # This shouldn't raise even though the child is now dead
+        getattr(p, method)(*args)
+        p.communicate()
+
     def test_send_signal(self):
         p = self._kill_process('send_signal', signal.SIGINT)
         _, stderr = p.communicate()
@@ -830,6 +851,18 @@ class POSIXProcessTestCase(BaseTestCase):
         self.assertStderrEqual(stderr, '')
         self.assertEqual(p.wait(), -signal.SIGTERM)
 
+    def test_send_signal_dead(self):
+        # Sending a signal to a dead process
+        self._kill_dead_process('send_signal', signal.SIGINT)
+
+    def test_kill_dead(self):
+        # Killing a dead process
+        self._kill_dead_process('kill')
+
+    def test_terminate_dead(self):
+        # Terminating a dead process
+        self._kill_dead_process('terminate')
+
     def check_close_std_fds(self, fds):
         # Issue #9905: test that subprocess pipes still work properly with
         # some standard fds closed
@@ -1126,6 +1159,31 @@ class Win32ProcessTestCase(BaseTestCase):
         returncode = p.wait()
         self.assertNotEqual(returncode, 0)
 
+    def _kill_dead_process(self, method, *args):
+        p = subprocess.Popen([sys.executable, "-c", """if 1:
+                             import sys, time
+                             sys.stdout.write('x\\n')
+                             sys.stdout.flush()
+                             sys.exit(42)
+                             """],
+                             stdin=subprocess.PIPE,
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE)
+        self.addCleanup(p.stdout.close)
+        self.addCleanup(p.stderr.close)
+        self.addCleanup(p.stdin.close)
+        # Wait for the interpreter to be completely initialized before
+        # sending any signal.
+        p.stdout.read(1)
+        # The process should end after this
+        time.sleep(1)
+        # This shouldn't raise even though the child is now dead
+        getattr(p, method)(*args)
+        _, stderr = p.communicate()
+        self.assertStderrEqual(stderr, b'')
+        rc = p.wait()
+        self.assertEqual(rc, 42)
+
     def test_send_signal(self):
         self._kill_process('send_signal', signal.SIGTERM)
 
@@ -1135,6 +1193,15 @@ class Win32ProcessTestCase(BaseTestCase):
     def test_terminate(self):
         self._kill_process('terminate')
 
+    def test_send_signal_dead(self):
+        self._kill_dead_process('send_signal', signal.SIGTERM)
+
+    def test_kill_dead(self):
+        self._kill_dead_process('kill')
+
+    def test_terminate_dead(self):
+        self._kill_dead_process('terminate')
+
 
 @unittest.skipUnless(getattr(subprocess, '_has_poll', False),
                      "poll system call not supported")
diff --git a/Misc/NEWS b/Misc/NEWS
index 0e06a1a41d7..c5c2c8225a6 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -18,6 +18,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #14252: Fix subprocess.Popen.terminate() to not raise an error under
+  Windows when the child process has already exited.
+
 - Issue #14195: An issue that caused weakref.WeakSet instances to incorrectly
   return True for a WeakSet instance 'a' in both 'a < a' and 'a > a' has been
   fixed.
diff --git a/PC/_subprocess.c b/PC/_subprocess.c
index 6780382e6ea..689b0c8b433 100644
--- a/PC/_subprocess.c
+++ b/PC/_subprocess.c
@@ -670,4 +670,5 @@ init_subprocess()
     defint(d, "WAIT_OBJECT_0", WAIT_OBJECT_0);
     defint(d, "CREATE_NEW_CONSOLE", CREATE_NEW_CONSOLE);
     defint(d, "CREATE_NEW_PROCESS_GROUP", CREATE_NEW_PROCESS_GROUP);
+    defint(d, "STILL_ACTIVE", STILL_ACTIVE);
 }