Server side rendering with phpv8/v8js on Ubuntu requires phpv8/v8js. Here is how to install the latest (at the time of writing) with php7.1.

Add the latest ppa from this guy:

Update the sources:

Install libv8:

Install and compile v8js

Optionally remove the files from the install from /tmp.

After this the SSR of the example vuejs app should work.