Vendor file path

How do I load a class in Vendor folder ?
I am trying to load this file :

I am updating from cake 2.x to 3.3.7

Was it installed with composer? If it’s a namespaced class, then it should be handled by the autoloader (composer dumpautoload to refresh that), and you can use it the same as any other class.

Was not :frowning: Installed old school !

You may need to add details in your own composer.json, then, to tell it about the namespace in that folder. See Manually Installing a Plugin.

OK. Thank you.
You are always a great help !