Hi guys,
I have been struggling with getting minification of W3TC to work with Trellis. Do you guys got it to work, and how?
W3TC is creating the /app/cache/minify/ folder, but it’s staying empty.
I would like to have all the wp-includes/*.js and *.css files combined at least.
Why use W3TC if you’re using Trellis?
Because I still would like minification (concatenation especially) of my css & js files, and I’m not using Roots.
And because w3tc has decent CDN support and other nice things.
I don’t think anyone on the Roots team has used W3TC in… years… but perhaps someone else has some experience. I don’t really know why it wouldn’t work though. Perhaps you can check your logs and see if there is an actual error when W3TC is running.
Found the error. W3TC is just not compatible with PHP7.
Because of my theme, I could not see the error.
The fix was very easy, but it seems that W3TC is not actively maintained anymore right now. 
Concerning minification, there is a recently maintained plugin that seems to work quite nicely, https://github.com/kasparsd/minit .