Thank you all for the help, did.
Debian GNU/Linux Jessie:
sudo service nginx stop
You need to paste the code in:
sudo service nginx start
I have no idea, where this bug is coming from, I just setup a clean nodebb installation on my local machine, and everything worked as expected.
When I open a page in the admin panel, it looks like this, and the page title is "acp-title"
After reloading the page via F5, the correct page title displays for half a second, until being replaced with "acp-title" again. The manual reloading causes the page to look a bit more correct, but only to about 80%
Outside of the admin panel everything works correct as well...
Any ideas where this could be coming from? The NodeBB installation I'm having issues with, runs on a Ubuntu 16.04 LTS server...
@RoiEXLab are you using nginx to reverse proxy? Are there any errors or warnings client side? You may be having this issue: https://community.nodebb.org/topic/10031/issue-with-admin-panel-since-upgrade-to-1-4-2/35
Thank you so much! That was the issue the whole time!
Can't thank you enough!