FP2 is stuck in TWRP after trying to update the OS

Hi there!
Yesterday my FP2 offered me a new OS update and as always I downloaded it and wanted to install it. After a short time the update got stuck at a point in which the blackbox of TWRP says:
Unable to find partition for path ‘/system’
Full SELinux support is present.
Now my phone is stuck in TWRP and I dont have any idea how that works. How can I get my phone running again?
Thanks a lot!

Using the search function I found several threads about such happenings.
And this specific thread.

I believe there is information that can help you to resolve this issue.