Actually, there are a few versions of PHP that have known bugs at the moment (and affecting a great many plugins and themes) – have you contacted your hosting provider? They may already be aware of the issue and rolling out an update for your version of PHP.
You haven’t provided any details, so I can’t really offer any help beyond that. If you’re seeing a generic 500 error, again, I would suggest you contact your hosting provider.
If you are experiencing any other kind of issue, I would suggest you activate the Query Monitor plugin, or define the WP_DEBUG constant — all fairly well known solutions to find / report issues. WPSSO uses many features of WordPress and may, on occasion, trigger bugs in other plugins. Both the Query Monitor and the WP_DEBUG constant would enable you to find out which plugin / theme is causing the issue. As far as I know, there are no known problems with the current version of WPSSO.
Reviews are not a support channel like the support forum, so I would suggest you contact your hosting provider, and if you need additional help, post to the WPSSO support forum. ??
Enjoy,
js.