Game won't load since 1.19.31 hotfix

Updated to 1.19.31 hotfix yesterday (4th Oct 2022) and game worked fine immediately afterwards.  However from this morning onwards when I try to launch Minecraft I get "Minecraft needs an update" - which I can't get round.  OKing the update puts it in the queue however it never actually starts updating, just sits there at 0% of 1.69GB forever.