This document will tell you how to upgrade from one version to one other.
-
You need to install a HTTP client that provides the virtual package php-http/client-implementation.
-
(Optinal) Add the client's service name to
cspoo_swiftmailer_mailgun.http_client
. (Preferably with help from HttplugBundle) -
You might have to remove your bootstrap.php.cache, clear your apcu cache and then re-run composer update.
Read more about how to use HTTPlug here: http://php-http.readthedocs.io/en/latest/httplug/users.html