Plugin Manager not working (self installed Octoprint on Linux)

Hi,
I am not able to install plugins. I followed this guide here https://discourse.octoprint.org/t/setting-up-octoprint-on-a-raspberry-pi-running-raspbian/2337 to install Octoprint on a Ubuntu 18.04 LTS Server. I have a own user "octoprint" for running Ocotprint and my /etc/default/octoprint is:

# Configuration for /etc/init.d/octoprint`

# The init.d script will only run if this variable non-empty.
OCTOPRINT_USER=octoprint

# base directory to use
BASEDIR=/home/octoprint

# configuration file to use
#CONFIGFILE=/home/pi/.octoprint/config.yaml

# On what port to run daemon, default is 5000
PORT=5000

# Path to the OctoPrint executable, you need to set this to match your installation!
#DAEMON=/opt/OctoPrint/venv/bin/octoprint
DAEMON=/usr/local/bin/octoprint

# What arguments to pass to octoprint, usually no need to touch this
DAEMON_ARGS="--port=$PORT"

# Umask of files octoprint generates, Change this to 000 if running octoprint as its own, separate user
#UMASK=022
UMASK=000

# Process priority, 0 here will result in a priority 20 process.
# -2 ensures Octoprint has a slight priority over user processes.
NICELEVEL=-2

# Should we run at startup?
START=yes

The Pluginmanager_console_log says:

2018-08-20 16:52:48,961   /usr/bin/python -m pip install linkkk_needed_to_be_removed_because_new_user_here --no-cache-dir --user
2018-08-20 16:52:49,971 > Collecting link...
2018-08-20 16:52:51,299 > Downloading link...
2018-08-20 16:52:51,299 > Collecting OctoPrint (from OctoPrint-EEprom-Marlin-Printrbot==0.1.0)
2018-08-20 16:52:51,300 ! Could not find a version that satisfies the requirement OctoPrint (from OctoPrint-EEprom-Marlin-Printrbot==0.1.0) (from versions: )
2018-08-20 16:52:51,300 ! No matching distribution found for OctoPrint (from OctoPrint-EEprom-Marlin-Printrbot==0.1.0)
2018-08-20 16:55:06,261   /usr/bin/python -m pip install link... p --no-cache-dir --user
2018-08-20 16:55:07,275 > Collecting link...
2018-08-20 16:55:08,571 > Downloading link...
2018-08-20 16:55:08,571 > Collecting OctoPrint (from OctoPrint-Pushover==0.2.1)
2018-08-20 16:55:08,571 ! Could not find a version that satisfies the requirement OctoPrint (from OctoPrint-Pushover==0.2.1) (from versions: )
2018-08-20 16:55:08,571 ! No matching distribution found for OctoPrint (from OctoPrint-Pushover==0.2.1)

I am pretty sure I messed up with some user rights, but I don't know where to look, the error log is giving me no hint.

Hi, I've still got that problem - but I came closer - I can manually update via shell when using the sudo command (sudo pip install https...).
So there is a problem with the rights - could anyone give me a hint where to look / what to change?
Thank you!

Are you using any of the venv-related commands? Python apps these days carve out their own virtual environments so that their own version of packages don't clash with other apps.

Read this thread for more info.

Hi, Developer of the pushover plugin here.

Does it work ? Maybe I can help ?