diff -r be25b66f86ab -r 8f50dc096cf4 mercurial/error.py
--- a/mercurial/error.py	Mon Nov 23 16:05:03 2020 -0800
+++ b/mercurial/error.py	Mon Nov 23 16:20:02 2020 -0800
@@ -216,6 +216,14 @@
     """
 
 
+class SecurityError(Abort):
+    """Indicates that some aspect of security failed.
+
+    Examples: Bad server credentials, expired local credentials for network
+    filesystem, mismatched GPG signature, DoS protection.
+    """
+
+
 class HookLoadError(Abort):
     """raised when loading a hook fails, aborting an operation