Migrate from Owncloud 10.3.1

I want to migrate from Owncloud 10.3.1 to Nextcloud. Which update path should work here or is this not possible? In the version.php from Nextcloud 18.0.1 I can see the following:

$OC_VersionCanBeUpgradedFrom = array (
  'nextcloud' => 
  array (
'17.0' => true,
'18.0' => true,
  'owncloud' => 
  array (

Which indicates an upgrade from Owncloud is impossible.

I have asked the same question without getting any answer. Seems that this forum is not very responsiveā€¦ I found, that I would need to migrate to Nextcloud 12 first and then to every next major version. Anyway I thought twice about running along a rather complicated multiple migration path (which is even not very popular according to the non-responses) and came to the conclusion that a fresh new install of Nextcloud and transferrring the documents from owncloud to Nextcloud via the clients is the least painful way. However, my userbase is small and I have not used much plugins, so the main tasks have been setup the new (Nextcloud) and deleting the old (owncloud) clients.

99%+ of us did not migrate from owncloud so we canā€™t help you.

Here is a walktrough: