The Drupal 8 upgrade is well worth the effort. Just be sure to follow these tips and prepare well.
We recommend not performing a Drupal 8 upgrade on a live site.
Unlike previous major upgrades, the change to Drupal 8 does not automatically upgrade your website in-place. Instead, it pulls in configuration information and content from the source site. The process does not modify your source site in any way, but it's still a good idea to do the upgrade on a site that is not live.
Before upgrading your site for a fresh installation of Drupal 8, do not configure the website, but do these things:
Are you experienced and/or confident with Drupal?
It can be very tough for a non-Drupalist to write code. Get help from established Drupal service experts.
Even if you are familiar, what if something goes wrong and you have to start over? Do you know how to run queries in the database to delete entities and drop tables created in the migration process? Again, it would be best to outsource for help. It will cost far less in time wasted.
The system for upgrading Drupal sites has been re-written for Drupal 8, largely inspired by the work of the Drupal 7 Migrate and Drupal-to-Drupal Data Migration modules. It is much more robust and the functionality of the new modules is greatly expanded so that they now handle both site configuration and content.
Migrate is now included in the Drupal core to make an easier pathway for upgrading from versions 6.x and 7.x to Drupal 8.
<Migrate>: Handles migrations. Contains core framework classes, destination, source and process plugins, schemas and definitions. At last, it also contains the migration config entity, schema and definition.
<Migrate Drupal>: Contains migrations from older Drupal versions. Includes implementations of destination, sources and process plugins for Drupal 6 and 7. But this module doesn't contain the configuration to migrate all data from your older Drupal site.
In the "process" folders, you can find examples that will help you write new ones. As with any open source, writing your own code is part of it all, so familiarize yourself with these samples. To find them, use these commands:
find ./ -type d -name 'migration_templates'
find ./ -type d -name 'process'
Upgrading from Drupal 6 to 8 is trickier than from 7 due to the changes in code.
Consider if it's time to rethink your content or even your overall content strategy. Drupal has always been at the forefront of structured content modeling and the toolkit has only expanded with this new version. Is now the time to start aiming your system to support a mobile app, or an even broader omni-channel strategy?
For Drupal 8 upgrade, as with any upgrade, there are always costs that make you wonder if you need an automatic solution or a developers writing software, or even if your in-house team should handle it.
A personal consultation to examine the cost of manual vs. automatic migration is always a wise idea.
Creative Commons Attribution: Permission is granted to repost this article in its entirety with credit to Snowbot and a clickable link back to this page.