[SOLVED] Can't access WebGUI after 7.2.2 stable upgrade

So let me begin with, I already managed to solve it, but I thought I'd share it here, for anyone running into the same issue.

So, I upgraded yesterday from 7.1.4 to 7.2.2, upon which everything seemed to have restarted correctly...
My VMs were running, I saw expected traffic from the unraid server on the firewall, SSH was working..... but I couldn't access the WebGUI.
When I tried, I was getting a connection reset.

Found some other threads reporting similar issues that made me worried....so went out to take diag and started to sift through the syslog.txt file.

The following log line showed me something didn't go very well :
rc.nginx: Nginx server daemon... Failed.

Following this comment I stopped and restarted nginx which showed me what exactly went wrong:
/etc/rc.d/rc.nginx start

rc.nginx: Starting Nginx server daemon...

Enter PEM pass phrase:

A week ago, I had implemented a new certificate, but yesterday I had also noticed, that when I opened the WebGUI, somehow the old certificate was still being used, despite showing to use the new one in the WebGUI. But I didn't think much of it, considered it would fix itself after the upgrade and subsequent reboot.
This new cert was installed with a passphrase enabled...and this was clearly what was the issue when rebooting...
The Passphrase had to be manually entered to start the WebGUI.

Long story short :
After upgrading an unraid server that has a certificate with passphrase, manually start nginx and enter said passphrase