For a recent project I needed the PHP extension Imagick. After running apt-get update and such commands on my puphpetvagrant installation I rebooted the virtual machine and my sites started getting errors regarding the utf8_decode() and simplexml_load_file() functions not existing. Even after destroying the instance and provisioning it from scratch it remained broken. Panic!
After some research it appeared I was missing some normally common XML modules in the PHP installation. Even though the PHP docs and any other resources claim SimpleXML is installed and active by default, it was not after my latest updates. Note that the server/php combo in question was Ubuntu 14.04 32bit + PHP 5.6.
The result of a bunch of research, headaches and guessing:
1. SSH into your machine
2. Check if the module SimpleXML is installed & active:
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