Just a thought, not a bug per se.
Shouldn't the PluginManager report Invalid plugins somehow? Version errors are detected and that's great but the PluginManager just ignores these and moves on to the next Plugin... fair enough..
But if a plugin is critical to the operation of the site, then we should somehow inform the admin with either an operator message or at least log the plugin name & error in the log. Granted, the admin should make sure his plugins are compatible b4 the upgrade but this will not always happen, leaving the admin scratching his head and the plugin developer getting support calls he shouldn't.
Regards,
Rock
