Hello,
For an upgrade from 5.0.8 to 5.1.1 I have errors with the following 3 
services :
Can you help me with eventengine et servicemon errors ?
For smsd the installation of the python-gammu package should solve this
I also had to install the package python3-distutils
nav -V start eventengine
Traceback (most recent call last):
   File "/usr/bin/eventengine", line 19, in <module>
     main()
   File 
"/opt/venvs/nav/lib/python3.7/site-packages/nav/eventengine/daemon.py", 
line 41, in main
     daemonize()
   File 
"/opt/venvs/nav/lib/python3.7/site-packages/nav/eventengine/daemon.py", 
line 80, in daemonize
     nav.daemon.daemonize(PIDFILE, stderr=open(LOGFILE, "a"))
PermissionError: [Errno 13] Permission denied: 
'/var/log/nav/eventengine.log'
Failed: eventengine
____________________________________________________________________
nav -V start servicemon
Traceback (most recent call last):
   File "/usr/bin/servicemon.py", line 175, in <module>
     main(args.foreground)
   File "/usr/bin/servicemon.py", line 153, in main
     logfile = open(conf.logfile, 'a')
PermissionError: [Errno 13] Permission denied: '/var/log/nav/servicemon.log'
Failed: servicemon
____________________________________________________________________
nav -V start smsd
2020-12-07 17:34:42,057 [INFO] [nav.smsd] Starting smsd.
2020-12-07 17:34:42,057 [WARNING] [nav.smsd.dispatcher] Failed to import 
GammuDispatcher: python-gammu not installed or misconfigured.
2020-12-07 17:34:42,057 [CRITICAL] [nav.smsd] Dispatcher configuration 
failed. Exiting. (No dispatchers available. None configured or all 
dispatchers failed permanently.)
Failed: smsd
Thank you
Regards
Biselx Nicoals