Updates between multiple major versions and downgrades are unsupported

FAQ
1

Problem:

A “updates between multiple major versions and downgrades are unsupported” message is shown during an update/upgrade

Description:

As the message is telling you, you have done an unsupported upgrade path. For example:

Original version: 8.0.2
Upgraded version: 8.2.6

In this case you have skipped the 8.1.x major upgrade which is unsupported as stated within the documentation. In order to find out between which versions your are stuck, check the following files in the ownCloud folder:

Original version: config/config.php -> version
Upgraded version: version.php -> OC_version

Solution:

You need to upgrade first to the latest available version of 8.1.x which is currently 8.1.8. For that specific scenario the following is recommended:

  1. Remove all files and folders of your oC installation folder except /data/ and /config/
  2. Download 8.0.13 from https://owncloud.org/changelog/
  3. Extract the content of the archive it into your oC installation folder
  4. Run the update via the webgui or the occ command line tool.

Afterwards repeat those steps with 8.1.8 and 8.2.6

Additional note if you’re using ownCloud via the official linux repositories:

Documentation how to do proper upgrades when using the linux repositories are available in the official documentation:

https://doc.owncloud.org/server/9.0/admin_manual/maintenance/package_upgrade.html#upgrading-across-skipped-releases

For the scenario defined above you need to do the following step:

  1. Add repository providing 8.0.x to your package manager
  2. Update the owncloud package via the package manager
  3. Run the update via the webgui or the occ command line tool

Afterwards repeat those steps with the repositories providing 8.1.8 and 8.2.6 (linked at https://owncloud.org/changelog/)

Official documentation:
https://doc.owncloud.org/server/9.0/admin_manual/maintenance/upgrade.html