* Runtime problems specific to macOS
-** Error message when opening Emacs on macOS
+** Error message about malicious software when opening Emacs on macOS
When opening Emacs, you may see an error message saying something like
this:
exception for Emacs and from now on you should be able to open it by
double-clicking on its icon, like any other app.
+** Error message about color list unarchiver when starting Emacs on macOS
+
+The error message looks like this:
+
+ Failed to initialize color list unarchiver:
+ Error Domain=NSCocoaErrorDomain Code=4864 "*** -[NSKeyedUnarchiver
+ _initForReadingFromData:error:throwLegacyExceptions:]: non-keyed archive cannot be decoded by NSKeyedUnarchiver"
+ UserInfo={NSDebugDescription=*** -[NSKeyedUnarchiver
+ _initForReadingFromData:error:throwLegacyExceptions:]: non-keyed archive cannot be decoded by NSKeyedUnarchiver}
+
+After showing this message, Emacs usually works normally.
+
+The usual reason for this is that the color file,
+~/Library/Colors/Emacs.clr, is stale or corrupted. The solution is to
+delete that file and restart Emacs.
+
** macOS doesn't come with libxpm, so only XPM3 is supported.
Libxpm is available for macOS as part of the XQuartz project.