diff -r a9bedc56f025 -r 5caec48d9a01 mercurial/extensions.py
--- a/mercurial/extensions.py	Mon Sep 20 14:16:10 2021 -0400
+++ b/mercurial/extensions.py	Mon Sep 20 14:21:18 2021 -0400
@@ -224,7 +224,7 @@
     minver = getattr(mod, 'minimumhgversion', None)
     if minver:
         curver = util.versiontuple(n=2)
-        extmin = util.versiontuple(minver, 2)
+        extmin = util.versiontuple(stringutil.forcebytestr(minver), 2)
 
         if None in extmin:
             extmin = (extmin[0] or 0, extmin[1] or 0)