Try the fix below:
I had the same problem.
To fix this do the following:
cd /etc
mv rndc.conf _rndc.conf
/scripts/fixrndc
It seems that the source of the problem is the /etc/rndc.conf
To test that the problem has been fixed, run /scripts/upcp(this is the script that runs every day and by calling the /scripts/fixrndc, creates a corrupt /etc/rndc.key) and then check if named is still running and /etc/rndc.key secret is valid.