Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
OMG! I was having the same error message "The procedure entry point EnumCalendarInfoExEx could not be located in the dynamic link library Kernel32.dll" So I checked to see what updates had been installed since I was in the office last week... KB4462157 on 1/18/2019. Uninstalled that one and Excel is now working! I hope this fix works for you as well.