Upgrades always bring a significant number of Plesk enhancements or even introduce new Plesk features and behavior. After an upgrade, Plesk increases its major or minor version:

• Typically, if an upgrade only improves the existing functionality, then Plesk increments its minor version number (e.g. from 10.3.0 to 10.3.1).
• If an upgrade includes more complex changes in Plesk, then the major version number is incremented (e.g. from 10.3.1 to 10.4.0).

Plesk Upgrades and Release Tiers

During its lifecycle, each major Plesk version passes through a number of development stages (see the diagram below). It is natural that in earlier stages, some newly implemented features may not be in their final state and may require some further modification. The functionality of such features in subsequent Plesk versions is improved as they receive more customer feedback over time. To indicate the stage of the current Plesk version, we assign one of the following release tiers to it: Testing release, Early Adopter release, General release, and Late Adopter release.

The decision on what tier to use is absolutely up to you. For example, consider upgrading to the early adopter release if you want to try new features before Plesk becomes generally available. On the other hand, if you want to get the solution that has received all major updates and is being successfully used by a number of service providers, wait until Plesk gets the late adopter release status (which may be a couple of months after the general release).

Once you have decided what version you need, set up Plesk to notify you when upgrades to the chosen version become available. After you select the version type in Tools & Settings > Update and Upgrade Settings, Plesk will check for upgrades once a day. When an upgrade with the selected release tier becomes available, Plesk will notify you on the Home > System Overview. Note that Plesk always notifies you when a version with a “higher” release tier becomes available. For example, if you set Plesk to notify you about early adopter releases, you will still receive all upgrade notifications about general and late adopter releases. However, if you decide to use only late adopter releases, notifications for all early adopter and general release upgrades will be skipped.

The diagram below shows the rough Plesk lifecycle (the version numbers are given only as examples and have no correlation with the real ones).

Applying Plesk Upgrades

As upgrades imply multiple changes in the product and may require significant downtime, Plesk does not apply them automatically. Instead, it displays upgrade notifications on the Home page. Once you receive such a notification, you can initiate the upgrade either from Home > System Overview or Tools & Settings > Updates and Upgrades at any time that suits you.

The scenario described above is called in-place upgrade as Plesk components are updated within one server. However, there is another way to upgrade Plesk - upgrade by transfer. This way implies transferring Plesk data to another server with a later version of Plesk. Upgrade by transfer is suitable, for example, when you want not only to upgrade Plesk but also to move it to a more productive server or another operating system. To learn more about differences between upgrade ways and get detailed instructions on upgrading Plesk, read the Deployment Guide.

Plesk Upgrades and License Keys

Note that some Plesk licenses do not grant permission to perform complex upgrades (upgrades that change the major version number: e.g. from 10.3.1 to 10.4.0). If you attempt to perform such an upgrade, Plesk will warn you about license limitations. Nevertheless, you will still be able to perform the upgrade. When it is finished, you will need to obtain and install the license key for the new Plesk version. For more information about installing a license key after an upgrade, refer to the section Upgrading Your License Key.

Notes on the In-Place Upgrading Procedure

• After upgrading to a new Plesk version, you will receive a report on the upgrade procedure. The notification message will include the event log and a list of installed packages if the upgrade has been successful. However, you may not receive any error notice if your mail server fails. In this case you can check for errors in the autoinstaller3.log file located in the /tmp directory on the server hard drive.
• All Plesk operations are suspended during installation of the so-called base packages that affect the Plesk’s core functionality.
• Starting from 10.3, Plesk provides the ability to install alternative component versions (PHP 5.3, MySQL 5.5, etc.) directly from the Updates and Upgrades page.