Failed to load class or interface 'SimpleXMLElement': the class or interface 'SimpleXMLElement' 
is not defined in the library map for any loaded phutil library.

https://secure.phabricator.com/T11725

 libargon2-0{u} libsodium23{u} php-apcu-bc{a} php-cli{u} php-pear{a} php-xml php7.2-cli{u} php7.2-common{u} php7.2-json{u} 
  php7.2-opcache{u} php7.2-readline{u} php7.2-xml{u} 

大概是 php5.6-xml 沒裝或版本錯。