Be careful with GET parameter names in WordPress

I’ve been getting confused about why an HTML form I’ve been building inside a WordPress shortcode has been getting redirected after submission. Turns out it was because I was using p as a name for a request variable, and that’s not allowed. It’s one of the names used by WordPress core; there are a few dozen of them.

I switched to prefixing my form’s input names with the name of the plugin, and all is well.