The migration of Webform module https://www.drupal.org/project/webform content from Drupal 7 to Drupal 8 is not trivial, since the module was totally redesigned for the Drupal 8 version.
Drupal 7 version of the module is based on specific Content Type and therefore each webform ended up represented as a Node.
Drupal 8 version changed drastically this design, moving to a more flexible and OOP oriented. Now webforms are based on configuration entities and submissions are content entities. So special migration path is needed. Fortunately community has approached this migration and issue and implemented the module webform_migration https://www.drupal.org/project/webform_migrate
Base on that module the workflow to have Webform data migrated to Drupal 8 it’s needed the following steps:
- Based on a Drupal 8 blank site
- Download and Install webform_migrate module on the site
- Enable webform_migrate module and dependencies
- Enable migrate and migrate_plus modules
- Import migration path configuration
- from the downloaded webform_migrate module open the folder /migration_templates/d7/
- you will need to import the two configuration yml files there, d7_webform.yml and d7_webform_submission.yml
- Go to Configuration -> Configuration synchronization -> Import -> Single item and then select as “Configuration type” “Migration”. and paste the content of each of the previous files in the textbox.
- You should see some success on importing the configuration.
Once done, you can proceed with the regular request for migration a Drupal 7 to Drupal 8 (http://entice.web.cern.ch/announcements/drupal-7-drupal-8-migration), specify in the support ticket that webform data is involved in the migration, so admins can check the result of the migration.