I’ve just started using Fluida — really nice theme!
I’m having an odd issue when installing Yoast SEO, however. If I activate the plug-in and try to use the “Customise” feature, I get a 500 Internal Error message. Deactivating it solves the issue.
Since you recommend the plug-in elsewhere in this forum, maybe you can advise?
Based on the symptoms it’s either a resource limit error (your site hitting the memory limit with the plugin activated) or the plugin was installed with corrupt files – to exclude this you can try reinstalling it.
The server error log should hold more useful information about the problem.