Hi Paul,
I’m sorry to hear about the issue you’ve had.
I know you posted that you’re using 1.9.9.9.7, but that error is for version 1.9.9.9.6, and was remedied immediately in version 1.9.9.9.7. Please see my response here regarding that issue. If you upgrade to 1.9.9.9.7, it will resolve the issue.
Also, please note that if your site is using a standalone Nginx server does not meet the plugin’s minimum requirements, and is not compatible with WP-SpamShield:
3. Your server must be configured to allow the use of an .htaccess file. The vast majority of users will have no issue here, because most web hosts allow this by default. However, if yours does not, you will need to contact them and ask them to enable it on your site. If they won’t, then it’s time to get a better web host. WordPress loses a lot of functionality if you don’t have use of .htaccess enabled, so this is important for full functionality of WordPress and other plugins as well.) Note: By definition, a standalone Nginx server would not meet this requirement, but an Apache/Nginx hybrid setup would. (Nginx is setup as a reverse-proxy in front of Apache. This type of setup offers high-performance and is recommended.)
WP-SpamShield has not ever supported standalone Nginx, and this is explained in more detail in the Known Issues and Plugin Conflicts.
If you have any further issues, please submit a support request at the plugin’s official support page, and we’ll be happy to help you resolve it.
— Scott