Updating from Varbase 8.x to 9.x
Read First Before Updating
Updating a Varbase SiteUnderstanding Varbase Updater Package1. Change Composer Version Before Updating
Varbase 8.8.7 and Older
Make sure that Composer version ~1 is in use in the development environment.
sudo composer self-update --1Remove the not Needed Drupal Library Installer Plugin
Remove "drupal/drupal-library-installer-plugin": "^0.3", from the composer.json file.
Varbase 8.8.8 and Newer
Make sure that Composer version ~2 is in use in the development environment.
2. Add Drush
3. Uninstall All Removed Components
A number of modules, themes, and libraries was removed from Varbase 9. That for Drupal 9 compatibility, or for change of selection to use better tools, and newer and better UI/UX themes.
Modules Had Been Removed
Themes Had Been Removed
4. Check All Required Contrib Modules in the Project
Example Module: Webform Mautic
Projects may or may not use this module. If it was required and used, check the following in the project page.

In case the module was not compatible with Drupal 9 yet, Follow with issues and the maintainer to make the module have a Drupal 9 Compatibility.
5. Check All Custom Modules in the Project
6. Check All Required Libraries
7. Run the Update Varbase Command
Facing issues? Do the steps to do after the commands. next step.
8. Steps to Do After the Command
On the step of updating from Drupal ~8 to Drupal ~9, a number of duplicate key "services" detected in YamlSymfony.php and Parser.php.
Drupal 8 is using Symfony 3 and Drupal 9 is using Symfony 4
What changes are there for third-party dependencies?
It is better to remove the composer.lock and vendor/ folder. Then do a composer install
Run Database update number of times. Until no updates are needed.
9. Remove Drush Before Deployment to Production
10. Set Composer Exit on Patch Failure to True
Please, DO NOT set the following in the composer.json for projects
It should be
On wanting to ignore any patch, please use patches-ignore
Have a look at Ignoring Patches a link for how to do this in the right way
Extending VarbaseIf it was changed in any way or the Varbase Updater had it changed. Please change it back to
It was sat true in the Vardot/varbase-project/composer.json for the following rezone.
If Varbase Layout Builder ~8.0 or ~9.0 were not Enabled in Old Sites
Only remove it from the root composer.json file for the project and do a
composer updateThe Varbase Layout Builder ~10.0 and all needed modules will be required in the default Varbase ~9.0 profile
Enable Varbase Layout Builder and Varbase Landing (Layout Builder) modules.