diff --git a/django/core/files/base.py b/django/core/files/base.py
index 85b3c21cba..159a98e52f 100644
--- a/django/core/files/base.py
+++ b/django/core/files/base.py
@@ -36,19 +36,26 @@ class File(FileProxyMixin):
     def __len__(self):
         return self.size
 
+    def _get_size_from_underlying_file(self):
+        if hasattr(self.file, 'size'):
+            return self.file.size
+        if hasattr(self.file, 'name'):
+            try:
+                return os.path.getsize(self.file.name)
+            except (OSError, TypeError):
+                pass
+        if hasattr(self.file, 'tell') and hasattr(self.file, 'seek'):
+            pos = self.file.tell()
+            self.file.seek(0, os.SEEK_END)
+            size = self.file.tell()
+            self.file.seek(pos)
+            return size
+        raise AttributeError("Unable to determine the file's size.")
+
     def _get_size(self):
-        if not hasattr(self, '_size'):
-            if hasattr(self.file, 'size'):
-                self._size = self.file.size
-            elif hasattr(self.file, 'name') and self.file.name is not None and os.path.exists(self.file.name):
-                self._size = os.path.getsize(self.file.name)
-            elif hasattr(self.file, 'tell') and hasattr(self.file, 'seek'):
-                pos = self.file.tell()
-                self.file.seek(0, os.SEEK_END)
-                self._size = self.file.tell()
-                self.file.seek(pos)
-            else:
-                raise AttributeError("Unable to determine the file's size.")
+        if hasattr(self, '_size'):
+            return self._size
+        self._size = self._get_size_from_underlying_file()
         return self._size
 
     def _set_size(self, size):