Thanks for getting back to me, Syam!

The message is generated by WordPress, of course. But if it doesn’t appear with your plugin deactivated and then starts to appear as soon as I activate your plugin, wouldn’t this suggest that the plugin has at least something to do with it?

I don’t have any other plugins that touch users/roles installed. Could you help me narrow down the kind of plugin that might cause such a conflict with your plugin?

Thanks!