Some Phabricator workflows fatal if gd is not installed. gd is a PHP extension used to manipulate images (for example: resizing thumbnails and compositing profile images).
Although we rely on gd for image-related features, we should generally have reasonable fallback behaviors when gd is not available, and Phabricator should mostly work without gd until administrators get around to installing it.
Trying to create a new project when php-gd is not installed, throws an error:
Call to undefined function imagecreatefromstring() /home/avive/devtools/phabricator/src/applications/files/builtin/PhabricatorFilesComposeIconBuiltinFile.php:131
We describe gd as "optional".
Also, selecting a built-in pokemon for a user's profile picture fails without gd ("This server only supports these image formats: .").