Updating to 0.19.6/0.19.11 is strongly encourage for all witnesses.
Bug Fixes for 0.19.6
There was a bug in how witness nodes were heuristically calculating the block size when generating a block that could lead a node to produce a block that was too large. (#2632)
Authority membership size was not being enforced and is now checked.
After disabling my witness and stopping steemd, I updated the steem repository to 0.19.6. Compilation and installation works without problems.
The compilation and installation of 0.19.6 was smooth. After doing systemctl start steemd.service, steemd runs 0.19.6.
In around ten hours, I will sign my next block. My witness server version will then be correctly be shown as 0.19.6.
I will switch to 0.19.11 in the near future.
Node is running 0.19.11
Will look into updating @humanheart's witness too, thanks.