Cannot subtract from an empty selection

[Ofnuts]

(01-14-2024, 02:41 PM)SteveNewcomb Wrote: This was a show-stopper for me.  The advice above did not help. 
The answer turned out to be a bogus saved tool option of some kind.  Here's what worked:

(1) Edit->Preferences->Tool Options->Reset Saved Tool Options To Default Values
(2) Restart gimp.

Actually Blighty's post #3 is the real answer. Your action has just reset the Selection tool to Replace mode which is its default.

if you want Gimp to always start with known options: see here.