IOTA Coordinator issue

Hi everyone! I recently faced with issue with my Coordinator in private IOTA network. I’m using this tutorial to set up my private tangle. The script, provided by described tutorial executes Coordinator which puts some milestones and after a while it is stopped, throwing following log message:

“PANIC Coordinator coordinator/plugin.go:234 failed to create: signature validation failed: %!w()”

I will be very happy if anybody can explain the reason of such issue and ways to resolve it (by the way, the days before this issue appeared, everything had been fine) Thank you in advance!