Read-only file system after Upgrade from OMV 5.x to 6.x via CLI

Hi there,

I finally found time to upgrade my OMV installation before EOL of OMV 5.x.

However the upgrade leaves me with a broken installation.

What have I done?
* I checked for any new packages via the OMV 5 GUI and ended up with version 5.6.26-1.

* I checked if my used plugins are OMV 5 compliant and it seems so. I am using: openmediavault-snapraid 5.0.8, openmediavault-unionfilesystems 5.1.4 and openmediavault-omvextrasorg 5.6.6

* I ran the command omv-release-upgrade as root

What have I observed?
The upgrade ended successfully (omv_upgrade.txt). But the web server was not reachable (code 404). Naturally, I observed the status of ngnix, which failed to start because of the read-only file system. I can manually remount the file system and also successfully start ngnix, but I get an 503 error if I try to login into the GUI afterwards. So there's obviously more.

* Rebooting sets the system in read-only again.

* I also tried https://raw.githubusercontent.…ipt/master/fix5to6upgrade without any issues, but ultimately did not help.

In difference to thread Upgrade 5 --> 6 failed miserably, system read only now, need help I have made a backup and already tried to repeat the upgrade process, but the result is always the same.

Note: I run OMV inside a proxmox VM (which shouldn't not be a concern, but I wanted to name it).

Did I do something wrong prior the upgrade?
Thank you for your help!

Clusters

I might have identified the issue myself.

The upgrade process does not like the openmediavault-unionfilesystems plugin.

This is how I got around that. Those steps shouldn't affect your filesystem. Meaning that you can safely return to a prior backup if something wrong happens. But no guarantee from my side

1. Make a backup if you don't have one yet.
2. Make sure to shut down systems that depend on your NAS/Samba/etc. shares.
3. Delete your pool in union file systems (GUI). Remember the file systems which were part of the pool.
4. Uninstall the union file systems plugin (GUI).
5. Install the usrmerge package with sudo apt-get install usrmerge (CLI). (I'm not sure if this step is really relevant)
6. Reboot your OMV system.
7. Perform the upgrade with omv-release-upgrade (CLI).
8. This should finish without any issues. Reboot the system afterwards.
9. Log into the new GUI and install the new plugin called openmediavault-mergerfs (GUI). It is normal that the config save throws an error.
10. Search and install updates in System Update -> Management -> Updates (GUI).
11. Create a new pool in Storage -> mergerfs (GUI). The storage should contain the same file systems as the pool that was deleted before the upgrade.
12. Create a new shared folder referencing to the newly created pool (GUI). It's just temporarely, you can name it whatever you want.
13. Go into the omv configuration with sudo nano /etc/openmediavault/config.xml (CLI).
    1. Search the newly created shared folder within the <sharedfolder> section.
    2. It should contain a <mntentref> item. Copy the reference ID between <mntentref> and </mntentref> into your clipboard.
    3. Replace the reference ID for all other shared folders within the <sharedfolder> section with that one you just copied into the clipboard.
    4. Save with Control + X and yes
14. Reboot OMV
15. Login into GUI and remove the temporarely created shared folder.
16. Do a config save, which should now be without any errors.
17. Start your systems which depend on your NAS/Samba/etc. they should work now.

Known issues so far:

• Windows does not like the changed folders and rejects to connect to them. I've got around that by connecting them again by using the IP address instead of the NAS DNS. But maybe there is a more elegant way fixing that.
• An other issue documented in Kernel from OMV 5.x is not upgraded after running omv-release-upgrade command

Hope this helps someone.