Warning: You are browsing the documentation for Symfony 4.0, which is no longer maintained.
Read the updated version of this page for Symfony 5.3 (the current stable version).
When a new patch version is released (only the last number changed), it is a release that only contains bug fixes. This means that upgrading to a new patch version is really easy.
To upgrade to a new "patch" release, read the Upgrading a Minor Version article. Thanks to Symfony's :doc`backwards compatibility promise </contributing/code/bc>`, it's always safe to upgrade to the latest "minor" version.
It is recommended to update to a new patch version as soon as possible, as important bugs and security vulnerabilities may be fixed in these new releases.
You may also want to upgrade the rest of your libraries. If you've done a
good job with your version constraints in
composer.json, you can do
this safely by running:
$ composer update
Beware, if you have some unspecific version constraints in your
dev-master), this could upgrade some
non-Symfony libraries to new versions that contain backwards-compatibility