@Mykle1 I tried your solution earlier but result was still the same.

I also managed to fix everything :)
I reinstalled whole rasbian, because I really messed up and when I tried to star MM directly on PI, it was showing only black screen. Then I installed MM directly on PI.
Earlier I was installing it via SSH. Shouldn’t be the issue yet it was…
Now everything runs smooth, I can start MM directly and via SSH with both commands DISPLAY=:0 nohup npm start & and DISPLAY=:0 npm start.

Thanks for all support :)

Update.
After reboot node and npm are up to date. However I still can’t start up MM via SSH. From PI terminal it works like a charm.

root@raspberrypi:~/MagicMirror# DISPLAY=:0 npm start

> magicmirror@2.4.1 start /root/MagicMirror
> sh run-start.sh

No protocol specified

(electron:942): Gtk-WARNING **: cannot open display: :0
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! magicmirror@2.4.1 start: `sh run-start.sh`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the magicmirror@2.4.1 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /root/.npm/_logs/2018-09-23T00_09_27_111Z-debug.log
root@raspberrypi:~/MagicMirror# DISPLAY=:0.0 npm start

> magicmirror@2.4.1 start /root/MagicMirror
> sh run-start.sh

No protocol specified

(electron:965): Gtk-WARNING **: cannot open display: :0.0
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! magicmirror@2.4.1 start: `sh run-start.sh`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the magicmirror@2.4.1 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /root/.npm/_logs/2018-09-23T00_09_42_728Z-debug.log

Error log:

root@raspberrypi:~/.npm/_logs# cat 2018-09-23T00_09_42_728Z-debug.log 
0 info it worked if it ends with ok
1 verbose cli [ '/usr/bin/node', '/usr/bin/npm', 'start' ]
2 info using npm@6.4.1
3 info using node@v10.11.0
4 verbose run-script [ 'prestart', 'start', 'poststart' ]
5 info lifecycle magicmirror@2.4.1~prestart: magicmirror@2.4.1
6 info lifecycle magicmirror@2.4.1~start: magicmirror@2.4.1
7 verbose lifecycle magicmirror@2.4.1~start: unsafe-perm in lifecycle true
8 verbose lifecycle magicmirror@2.4.1~start: PATH: /usr/lib/node_modules/npm/node_modules/npm-lifecycle/node-gyp-bin:/root/MagicMirror/node_modules/.bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
9 verbose lifecycle magicmirror@2.4.1~start: CWD: /root/MagicMirror
10 silly lifecycle magicmirror@2.4.1~start: Args: [ '-c', 'sh run-start.sh' ]
11 silly lifecycle magicmirror@2.4.1~start: Returned: code: 1  signal: null
12 info lifecycle magicmirror@2.4.1~start: Failed to exec start script
13 verbose stack Error: magicmirror@2.4.1 start: `sh run-start.sh`
13 verbose stack Exit status 1
13 verbose stack     at EventEmitter.<anonymous> (/usr/lib/node_modules/npm/node_modules/npm-lifecycle/index.js:301:16)
13 verbose stack     at EventEmitter.emit (events.js:182:13)
13 verbose stack     at ChildProcess.<anonymous> (/usr/lib/node_modules/npm/node_modules/npm-lifecycle/lib/spawn.js:55:14)
13 verbose stack     at ChildProcess.emit (events.js:182:13)
13 verbose stack     at maybeClose (internal/child_process.js:962:16)
13 verbose stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:251:5)
14 verbose pkgid magicmirror@2.4.1
15 verbose cwd /root/MagicMirror
16 verbose Linux 4.14.70-v7+
17 verbose argv "/usr/bin/node" "/usr/bin/npm" "start"
18 verbose node v10.11.0
19 verbose npm  v6.4.1
20 error code ELIFECYCLE
21 error errno 1
22 error magicmirror@2.4.1 start: `sh run-start.sh`
22 error Exit status 1
23 error Failed at the magicmirror@2.4.1 start script.
23 error This is probably not a problem with npm. There is likely additional logging output above.
24 verbose exit [ 1, true ]

@grimorth Update. I managed to get rid of all node versions and installed 10.0 but I can’t start npm now. It says
root@raspberrypi:~/MagicMirror# npm -v -su: /usr/local/bin/npm: No such file or directory

I tried apt-get install npm but without luck…

@mykle1 Okay, that’s a good start, however I just messed up. I tried to update node, but it said that it’s already in the newest version (10.0) but as you pointed out npm shows 4.2.1, so I decided to completely remove node and install it again. I deleted some folders under /usr/local/lib and /usr/local/include, however it’s still shows that node is installed. Can you help me get rid of it and reinstall? Also maybe reinstall of whole MM would be helpful?

Hello,
This is my first post here, so I would like to greet everyone! :)

So I installed MM on my PI 3 v1.2 year 2015, and I tried to start it via SSH.
Of course I read manual and I’m trying to start it by DISPLAY=:0 npm start

But it’s giving me this error

root@raspberrypi:~/MagicMirror# DISPLAY=:0 npm start

> magicmirror@2.4.1 start /root/MagicMirror
> sh run-start.sh

No protocol specified

(electron:2352): Gtk-WARNING **: cannot open display: :0

npm ERR! Linux 4.14.70-v7+
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "start"
npm ERR! node v4.2.1
npm ERR! npm  v2.14.7
npm ERR! code ELIFECYCLE
npm ERR! magicmirror@2.4.1 start: `sh run-start.sh`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the magicmirror@2.4.1 start script 'sh run-start.sh'.
npm ERR! This is most likely a problem with the magicmirror package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     sh run-start.sh
npm ERR! You can get their info via:
npm ERR!     npm owner ls magicmirror
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /root/MagicMirror/npm-debug.log

What is strange when I typed echo $DISPLAY on PI it showed value 0.0, so I also tried DISPLAY=:0.0 npm start but the result is still the same…

Some specs:
I’m using ssh via MacBook Pro Mid 2014, Mac OS High Sierra 10.13.6
Fresh install of Rasbian Stretch, kernel 4.14.70-v7+

Please help :C