Ubuntu version unknown is not supported by capistrano-mb. Only Ubuntu 16.04 is supported. Downgrade capistrano-mb if you need to use an older version of Ubuntu.

[nahankid]

Running lsb_release -a on Azure VM gives:

# lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 16.04.3 LTS
Release:	16.04
Codename:	xenial

However, cap staging provision fails with error:
Caused by:
Ubuntu version unknown is not supported by capistrano-mb. Only Ubuntu 16.04 is supported. Downgrade capistrano-mb if you need to use an older version of Ubuntu.

[mattbrictson]

Thanks for the report! I wonder why this doesn't work for you. On my Linode VM where capistrano-mb works, lsb_release -a gives:

No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 16.04.4 LTS
Release:	16.04
Codename:	xenial

Behind the scenes, capistrano-mb is actually running sudo lsb_release -a, so maybe there is a problem with sudo that is preventing the command from running?

Check log/capistrano.log if you haven't done so already to see if there is more information. Mine shows:

  INFO START 2018-03-10 18:02:43 -0800 cap staging mb:aptitude:check
  INFO ---------------------------------------------------------------------------
 DEBUG [c9521e5e] Running /usr/bin/env sudo lsb_release -a as root@[REDACTED]
 DEBUG [c9521e5e] Command: /usr/bin/env sudo lsb_release -a
 DEBUG [c9521e5e] 	Distributor ID:	Ubuntu
Description:	Ubuntu 16.04.4 LTS
Release:	16.04
Codename:	xenial
 DEBUG [c9521e5e] 	No LSB modules are available.
 DEBUG [c9521e5e] Finished in 0.594 seconds with exit status 0 (successful).