package multipath-tools 0.8.8-1ubuntu1 failed to install/upgrade: installed multipath-tools package post-installation script subprocess returned error exit status 1

The interessting part of the Error message is:
```
Failed to restart multipath-tools.service: Unit multipath-tools.service failed to load properly, please adjust/correct and reload service manager: File exists
See system logs and 'systemctl status multipath-tools.service' for details.
invoke-rc.d: initscript multipath-tools, action "restart" failed.
○ multipath-tools.service
     Loaded: error (Reason: Unit multipath-tools.service failed to load properly, please adjust/correct and reload service manager: File exists)
     Active: inactive (dead)
Warning: The unit file, source configuration file or drop-ins of multipath-tools.service changed on disk. Run 'systemctl daemon-reload' to reload units.
```

After reboot this is still the case:
```
root@resolver-test:~# systemctl status multipath-tools.service
Warning: The unit file, source configuration file or drop-ins of multipath-tools.service changed on disk. Run 'systemctl daemon-reload' to reload units.
○ multipath-tools.service
     Loaded: error (Reason: Unit multipath-tools.service failed to load properly, please adjust/correct and reload service manager: File exists)
     Active: inactive (dead)
root@resolver-test:~# systemctl restart multipath-tools.service
Failed to restart multipath-tools.service: Unit multipath-tools.service failed to load properly, please adjust/correct and reload service manager: File exists
See system logs and 'systemctl status multipath-tools.service' for details.
root@resolver-test:~# journalctl -u multipath-tools.service
-- No entries --
root@resolver-test:~# systemctl status multipath-tools.service
Warning: The unit file, source configuration file or drop-ins of multipath-tools.service changed on disk. Run 'systemctl daemon-reload' to reload units.
○ multipath-tools.service
     Loaded: error (Reason: Unit multipath-tools.service failed to load properly, please adjust/correct and reload service manager: File exists)
     Active: inactive (dead)
root@resolver-test:~# systemctl daemon-reload
root@resolver-test:~# systemctl restart multipath-tools.service
Failed to restart multipath-tools.service: Unit multipath-tools.service failed to load properly, please adjust/correct and reload service manager: File exists
See system logs and 'systemctl status multipath-tools.service' for details.
root@resolver-test:~# systemctl status multipath-tools.service
Warning: The unit file, source configuration file or drop-ins of multipath-tools.service changed on disk. Run 'systemctl daemon-reload' to reload units.
○ multipath-tools.service
     Loaded: error (Reason: Unit multipath-tools.service failed to load properly, please adjust/correct and reload service manager: File exists)
     Active: inactive (dead)

```

multipath-tools is depended by ubuntu-server but not really used.

Even purging it fails:

```
root@resolver-test:~# aptitude purge multipath-tools
The following packages will be REMOVED:
  multipath-tools{p}
0 packages upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
Need to get 0 B of archives. After unpacking 1,256 kB will be freed.
Do you want to continue? [Y/n/?] y
(Reading database ... 182822 files and directories currently...

Afterwards the unit is masked:
```
root@resolver-test:~# systemctl status multipath-tools
○ multipathd.service
     Loaded: masked (Reason: Unit multipathd.service is masked.)
     Active: inactive (dead)

```

Hello and thanks for this bug report. I tried doing a `do-release-upgrade -d` from Focal to Jammy, checking that multipathd was healthy in the first place, before beginning the upgrade. I couldn't reproduce the issue.

We're willing to investigate this failure case, but what we need are some steps to reproduce it starting from a clean Ubuntu system. Could you please provide us with those, and any other bit of context that can help us better understand what's happening? Thanks!

After thinking a while about this, and having a look at our configuration for focal I thik the reason for this issue during the upgrade is that the `multipathd.service` and `multipathd.socket` were already masked in our focal setup.
The `multipath-tools` packet is nevertheless attempting to restart them and this obviously fails.

We had diskussed to remove/purge the `multipath-tools` due to a massive amount of the following messages in focal:
```
multipathd[696]: sda: add missing path
multipathd[696]: sda: failed to get udev uid: Invalid argument
multipathd[696]: sda: failed to get sysfs uid: Invalid argument
multipathd[696]: sda: failed to get sgio uid: No such file or directory
multipathd[696]: sdb: add missing path
multipathd[696]: sdb: failed to get udev uid: Invalid argument
multipathd[696]: sdb: failed to get sysfs uid: Invalid argument
multipathd[696]: sdb: failed to get sgio uid: No such file or directory
```

And due to the dependency of the `ubuntu-servers` metapackage we decided to mask the `multipathd.service` and `multipathd.socket` units.

Thank you for the followup, Lars.

Based on your comment (and if I understood it correctly), the issue was caused because of a local configuration choice instead of a bug in the package itself. Therefore, I'm closing this bug as Invalid. Feel free to reopen it and provide more details if you don't agree with the decision.

Thanks.