diff --git a/Lib/test/test_cmd_line_script.py b/Lib/test/test_cmd_line_script.py
--- a/Lib/test/test_cmd_line_script.py
+++ b/Lib/test/test_cmd_line_script.py
@@ -222,6 +222,22 @@
     def test_repl_stderr_flush_separate_stderr(self):
         self.check_repl_stderr_flush(True)
 
+    #@cpython_only
+    #@unittest.skipUnless(os.name == 'nt', 'requires Windows')
+    def testClosingStderr_issue19050(self):
+        # Run a Python subprocess interactively
+        with self.interactive_python(True) as p:
+            p.stdin.write(b'import os\n')
+            p.stdin.write(b'os.close(2)\n')
+            p.stdin.write(b'1/0')
+            for line in p.stdout: print(line)
+            p.stdin.write(b'import sys ; sys.exit(42)\n')
+
+        print(p.returncode)
+        p.wait()
+        self.assertEqual(p.returncode, 42)
+
+
     def test_basic_script(self):
         with temp_dir() as script_dir:
             script_name = _make_test_script(script_dir, 'script')
diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
--- a/Lib/test/test_fileio.py
+++ b/Lib/test/test_fileio.py
@@ -10,6 +10,7 @@
 from functools import wraps
 
 from test.support import TESTFN, check_warnings, run_unittest, make_bad_fd, cpython_only
+from test import script_helper
 from collections import UserList
 
 from _io import FileIO as _FileIO
diff --git a/Parser/myreadline.c b/Parser/myreadline.c
--- a/Parser/myreadline.c
+++ b/Parser/myreadline.c
@@ -115,6 +115,11 @@
     if (p == NULL)
         return NULL;
 
+    if (!_PyVerify_fd(fileno(sys_stdout)) ||
+        !_PyVerify_fd(fileno(stderr))) {
+        PyMem_RawFree(p);
+        return NULL;
+    }
     fflush(sys_stdout);
     if (prompt)
         fprintf(stderr, "%s", prompt);