I think there may be a slight problem with updating Schematics,(renaming nets) then performing a "Forward Design Changes" to the pcb from within the Schematic Editor.
I have experienced the dreaded "Unrecoverable Error" several times since upgrading to V28.0.0.
However, if I perform an Integrity check on the unmodified pcb in the PCB Editor and then perform a Forward Design Change within the PCB Editor, all works fine.