diff -r 9f33d12f6f48 -r 698ffff7024b mercurial/sslutil.py
--- a/mercurial/sslutil.py	Thu Apr 13 04:12:31 2023 +0200
+++ b/mercurial/sslutil.py	Thu Apr 13 11:28:48 2023 +0200
@@ -553,7 +553,7 @@
 
         # This config option is intended for use in tests only. It is a giant
         # footgun to kill security. Don't define it.
-        exactprotocol = ui.config(b'devel', b'serverexactprotocol')
+        exactprotocol = ui.config(b'devel', b'server-insecure-exact-protocol')
         if exactprotocol == b'tls1.0':
             if b'tls1.0' not in supportedprotocols:
                 raise error.Abort(_(b'TLS 1.0 not supported by this Python'))
@@ -583,7 +583,8 @@
             sslcontext.maximum_version = ssl.TLSVersion.TLSv1_2
         elif exactprotocol:
             raise error.Abort(
-                _(b'invalid value for serverexactprotocol: %s') % exactprotocol
+                _(b'invalid value for server-insecure-exact-protocol: %s')
+                % exactprotocol
             )
     else:
         # Despite its name, PROTOCOL_SSLv23 selects the highest protocol that both
@@ -594,7 +595,7 @@
 
         # This config option is intended for use in tests only. It is a giant
         # footgun to kill security. Don't define it.
-        exactprotocol = ui.config(b'devel', b'serverexactprotocol')
+        exactprotocol = ui.config(b'devel', b'server-insecure-exact-protocol')
         if exactprotocol == b'tls1.0':
             if b'tls1.0' not in supportedprotocols:
                 raise error.Abort(_(b'TLS 1.0 not supported by this Python'))
@@ -609,7 +610,8 @@
             protocol = ssl.PROTOCOL_TLSv1_2
         elif exactprotocol:
             raise error.Abort(
-                _(b'invalid value for serverexactprotocol: %s') % exactprotocol
+                _(b'invalid value for server-insecure-exact-protocol: %s')
+                % exactprotocol
             )
 
         # We /could/ use create_default_context() here since it doesn't load