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Saurabh Dhariwal
Saurabh Dhariwal

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Migrating Legacy Drupal Sites to Drupal 9: Strategies for Smooth Transition

With the advancement of the Drupal community, so must the websites built on its robust platform. With the release of Drupal 9, many organizations face the critical task of updating their legacy Drupal sites. The advantages of migrating older versions in terms of performance, security, and also as regards new features and improvements are well known. Nevertheless, the process can get complex and issue-ridden. To this end, here are some tips on how to smoothly migrate legacy Drupal sites into Drupal 9.

Key Strategies for Migration Against Legacy Drupal Sites to Drupal 9

Before a developer gets into the actual migration, there is a need to know why they should upgrade to Drupal 9. Drupal 8 came with innovations but is near its life cycle. Staying with older versions will result in security vulnerabilities, lack of support, and missed opportunities for enhancement. Drupal 9 is built on the basis of its predecessor, incorporating a more modern codebase, thereby making it easier for developers to work with and implement new features.

Before Migration

  1. Assessment and Inventory Conduct an assessment of your current site and its content.  This includes taking an inventory of:
    • Installed modules and their level of compatibility with Drupal 9.
    • Themes and customizations that may need redevelopment.
    • Content types, fields, and taxonomy used throughout the site.

This list will form the basis of your migration strategy, pointing out areas that need amendment.

  1. Compatibility Checks
    You can run certain tools such as the module Drupal Upgrade Status to check if your website is ready for migration. The module can track the deprecated APIs and incompatible extensions on your site. The intention here is always to identify and correct issues regarding compatibility with current components on your existing site before moving further.

  2. Creating a Development Environment Set up a dedicated development environment during the migration process. In this way, you are free to work on the upgrade without affecting the site functionality. A staging site is also a great opportunity for productive testing that does not compromise the live environment.

Migration Strategies

1. **Direct Upgrade vs. Incremental Upgrade

One of the first decisions to make is whether to perform a direct upgrade from your current version to Drupal 9 or to follow an incremental upgrade path:

Direct Upgrade: If your current Drupal version is 8.8 or later, a direct upgrade to Drupal 9 is possible. This method leverages the upgrade tools provided by Drupal core to facilitate a relatively straightforward transition.

Incremental Upgrade: For those on older versions (such as Drupal 7), an incremental upgrade route may apply. This typically involves first moving to Drupal 8 and then from Drupal 8 to 9. This may take more time but can make the process more manageable, particularly for larger sites.

2. **Content Migration

Possibly the most painful part of upgrading is the content migration. Here, there are tools available in Drupal called the Migrate API to help with this process:

Use the Migrate Module: The Migrate module is part of Drupal core to migrate entities, fields and taxonomy. Plan how each piece of content will be migrated.

Field Mapping: Ensure that all fields used in your old site are available and correctly mapped in the new site to avoid data loss. Be aware of any changes in the field names or types from Drupal 7 to 9.

Testing Content Migration: After mapping, run test migrations in your development environment to identify any issues early. Look closely at content integrity, formatting, and accessibility.

3. Managing Custom Modules and Themes

Custom modules and themes frequently demand special attention during a migration process:

  • Update Custom Modules: Determine whether your custom modules should be updated to accommodate Drupal 9's standards. This can be updated with new APIs, replacing deprecated functions, or ensuring compatibility with the latest coding practices.

  • Themes Migration: Legacy themes can be checked for their possible updates to compatibility with Drupal 9 or rebuilt using the new theming system (Twig) provided by Drupal 8 and 9.

4. Automating with Tools

Take advantage of automation to reduce the burden of manual updates:

  • Drush and Composer: Use Drush for command-line tasks, while using Composer can really simplify dependencies management. Such tools will make it easier to handle multiple upgrades and maintain module compatibility.

  • Automated Tests: Implement automated testing (unit tests, functional tests) to ensure that new changes do not introduce regressions and are stable. This is especially important when migrating custom code.

Post Migration Considerations

1. Testing and Quality Assurance

Once the migration is complete, rigorous testing should be done:

Functional Testing: All functionalities of the site must be tested. Forms, workflows, and user permissions should work according to the migrated version.

Performance Testing: Compare the performance of the site with the legacy version. Google PageSpeed Insights would be of assistance in quantifying how much the speed and user experience have improved.

User Acceptance Testing (UAT): Get end-users into testing the site to make sure it indeed meets their needs and expectations before it goes live.

2. Rolled Back Plan Creation

Always have a rolled-back plan in case something goes wrong:

Backup Your Data: Before fully deploying new sites, always ensure you have backups of your old and new databases as well as the files on the site.

Ease of Rollback: Ensure that reverting to the legacy site is straightforward in case some critical issues crop up after the launch.

3. Training and Documentation

Following the launch of the new version, ensure to conduct training for the content administrators and owners of the site so that they know how to handle the new version and make maximum use of its features.

Documentation: Develop clear documentation on the architecture of the site, its features, and how-to guides on best practices in content management.

4. Ongoing Maintenance

Drupal 9 is an end-to-end platform that represents a stable and long-term solution; however, your site will require continuous maintenance to stay secure and up-to-date:

Stay Aware: Always be up-to-date with the latest info from the Drupal community concerning new best practices, security patches, and features.

Plan for Future Upgrades: With time, keep an eye on upcoming releases of Drupal and plan for future upgrades to ensure you are always on a supported version.

Conclusion

That is a big, involved job with huge gains in performance, security, and user experience-a properly executed process of migrating Drupal sites to Drupal 9. As organizations take a structured approach to assessing current sites, developing best-in-class tools, and executing their migration strategy with care, the process will be ensured as smoothly as possible. All this investment will pay off in enjoying your Drupal site long after the rest of your digital presence has moved on.

Success in navigating this upgrade serves not only to enhance the site for administrators and developers but also provides visitors with a richer, more engaging experience. Take this opportunity to refresh your site and take full advantage of what Drupal 9 has to offer.

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