Getting errors while developing plugins
You're getting "Couldn’t save the new user: Array" because $newUser-&gt;getErrors() returns an array of validation errors (in case there are more than one).

If you want to print them all to a log file, you can do something like this:

AutoUserEntryPlugin::log('Couldn't save the new user: '.implode(', ', $newUser-&gt;getErrors()), LogLevel::Info);