diff --git a/mercurial/extensions.py b/mercurial/extensions.py
--- a/mercurial/extensions.py
+++ b/mercurial/extensions.py
@@ -706,6 +706,10 @@
     '''find paths of disabled extensions. returns a dict of {name: path}'''
     import hgext
 
+    # __file__ not always present.
+    if not util.safehasattr(hgext, "__file__"):
+        return {}
+
     extpath = os.path.dirname(
         os.path.abspath(pycompat.fsencode(hgext.__file__))
     )