Natural Startup Error: 35

Hello guys, I’m new to this forum as well as new to Adabas/Natural.
this is my scenario. adabas/natural is running on HP-UX 11.31. It has been running for years fine.
recently, they asked me to make a clone of the entire OS so they can have a mirror on another Datacenter.
Adabas starts just fine, however, when trying to start natural, it shows this message:
$ natdesa

    NATURAL V 6.3.12 PL 0   Software AG 2012

    Natural Startup Error:  35

    Internal WFC i/o terminal driver error.

Since I’m new to this DB, I don’t even know where the log files are located, and how to troubleshoot this error.
I’d appreciate any help and reference links.
Thanks in advance.

Prior to invoking Natural, did you run (i.e. source) to set up the environment variables?

Does the existing system require a specific NATTERM environment variable setting that you are missing?