Cleaning up Legacy Fast Track?!

Hi, anyone know what this is about? On mobile I clicked on Dashboard and the above message came up. Now I can neither continue nor get out of the turning cog, app now totally unusable, and stuck! Very worried that this will infect all my work.

Later: Silly me, suddenly remembered the usual advice, shut everything down, reboot - and were back on track. Apologies for panic but it may serve as a reminder to others who can’t get rid of the cog; -)