Custom (a.k.a. contributed) modules are libraries of code that specialize in performing or enhancing specific tasks and which are not part of the core functionality of the CMS platform. Core modules, on the other hand, are those libraries that are essential to running a Drupal application and on which the entire system relies to perform its duties.
Updating Drupal modules is often straightforward and automated, there are still “gotchas” that need to be checked before those are deployed. Breaking a live site by performing an update to a custom module is not uncommon, and the steps necessary to perform an upgrade to the core of the Drupal system are often daunting.
VTL has developed the processes, tools and knowledge that enable us to to perform those upgrades seamlessly, without risking the stability of your system of breaking the chain of dependencies that your custom information architecture relies on. You can count on VTL to manage and perform Drupal upgrades safely.