I had the exact similar problem. I found no solution. Since I was working on a development server, I decided to create a fresh instance, while ignoring the one already there. By the way I did an upgrade from 8.1.5 to 8.1.6. The old instance was 8.1.5 and trying to connect using svrmgrl failed with this error. All I was trying to do is to upgrade this 8.1.5. instance to 8.1.6. The newly created instance has no such problems.