If I open a focal manipulator while it is upgrading a default lumos focus (only frugal upgrades, no glow pet/lumos maxima), I am kicked out of my world with the message "A fatal error has occured, this connection is terminated." Once the focus is done upgrading, I can open the manipulator just fine, until I start upgrading again.

Fixed.

I believe it is because I called a null if the focus is upgraded with neither the Glowpet or Maxima upgrades. I will fix this for the next patch.