I had gotten a similar error myself. So I deleted the plugin and then the error went away. But then I re-installed the plugin, but now, I can’t activate the plugin. It tries to activate, but it doesn’t. Something must have happened when I had the initial problem (where my entire site actually went down – until I deleted the plugin) and now I can’t activate WP Hide Post. It keeps sending me back out to the front end of my website.
I’m using WP 4.8, PHP version is 5.6.31
Any ideas?
Gary