--- a/Lib/shutil.py
+++ b/Lib/shutil.py
@@ -1072,7 +1072,7 @@
     if columns <= 0 or lines <= 0:
         try:
             size = os.get_terminal_size(sys.__stdout__.fileno())
-        except (NameError, OSError):
+        except (AttributeError, OSError):
             size = os.terminal_size(fallback)
         if columns <= 0:
             columns = size.columns

--- a/Lib/test/test_shutil.py
+++ b/Lib/test/test_shutil.py
@@ -1857,6 +1857,31 @@
 
         self.assertEqual(expected, actual)
 
+    def test_os_without_get_terminal_size(self): #26801
+        """Don't fail if os.get_terminal_size() doesn't exist."""
+        get_terminal_size = getattr(os, "get_terminal_size", None)
+        if get_terminal_size is not None:
+            del os.get_terminal_size
+
+        # make sure the function gets to (try to) call os.get_terminal)_size
+        # by removing all environment variables if they exist
+        columns = os.environ.pop("COLUMNS", None)
+        lines = os.environ.pop("LINES", None)
+
+        try:
+            result = shutil.get_terminal_size()
+        except AttributeError:
+            self.fail("shutil.get_terminal_size() failed with AttributeError")
+
+        # re-insert environment variables (if applicable)
+        if columns is not None:
+            os.environ["COLUMNS"] = columns
+        if lines is not None:
+            os.environ["LINES"] = lines
+
+        # add back get_terminal_size to the os module
+        if get_terminal_size is not None:
+            os.get_terminal_size = get_terminal_size
 
 class PublicAPITests(unittest.TestCase):
     """Ensures that the correct values are exposed in the public API."""