Hello, this plugin requires PHP >= 5.4
https://github.com/maratbn/RobotsWhiz/blob/master/REQUIREMENTS
I just noticed that this information is not displayed at https://wordpress.org/plugins/robotswhiz/ so I’m planning to update that with the next release.
Are you using PHP >= 5.4?
If you’re not sure try using this plugin to find out:
https://wordpress.org/plugins/display-php-version/
I’m on PHP 5.3 — That the highest my host provides at the moment. Too bad.
You might consider adding a version test to the plugin itself so that it gives the user an informative error message, rather than the fatal error I got.
There is already a version test in the logic, but PHP <= 5.3 errors-out before it can be reached.
Work-arounds for that would add a slight performance penalty for each HTTP request to the site, which is just not worth it for the vast majority of users running some more recent PHP.
The crux of this problem is that WordPress does not currently support PHP minimum version enforcement for themes and plugins.
https://core.trac.wordpress.org/ticket/23880
