@gevcen
Ask your Hosting Provider to Whitelist the mod_sec rule and maybe show them this Post.
Ok my Hosting Provider solved this Problem by whitelisting the mod_sec rule. Thanks for the Note @elenaocone @bungeshea
@elenaocone thanks, will try later
@rolevine ah ok yes its very strange. On my local WordPress Installation Snippets works fine. But on Online Website it didnt work. But I tested it only on one Site because I didn’t need it on other sites.
Maybe there’s a Conflict with Theme or Plugin?
Same problem, help please.