Migrating ownCloud 10.4.1 to nextcloud 18 Odyssee

Migrating ownCloud to nextcloud typically isn't that hard thank to the nextcloud developers who provide a user friendly migration script: https://nextcloud.com/migration/

Sadly at the moment the migration script only supports ownCloud migrations up to 10.0.x and not 10.x.

1) Old PHP Versions

Drupal 7 Migrate Module: Migration not working with result "Processed 0 (0 created, 0 updated, 0 failed, 0 ignored)" even if there are entries to process

Some days ago I had to program a bigger import for a Drupal 7 Forum, including several hundreds of thousands of entries and comments. I decided to use the Drupal migrate.module as helper for this import and it was a good decision!

migrate.module made things much easier and reduced the amount of custom import code.