Today I noticed the REDIRECT_UNIQUE_ID variable in the $_SERVER array, which I hadn’t noticed before. It had the value ‘ThpLM3U6@wYAADOTytg’.

Does anyone know what this variable is for? Googling didn’t help much, it just gave me instances of the variable in error pages.

I think it comes from the mod_unique_id Apache module.

mod_unique_id - Apache HTTP Server

AFAIK, it’s used to identify the process when using FCGI. :slight_smile: