Is it an error or is it a warning? Warnings are just there to have you double check things. If the warning doesn't apply to you, or you are sure you have the right information entered, then it's ok to ignore them.

what if it's not a warning, but actually shows as an error? 
There wasn't a problem, until I did a Turbo Tax update two days ago. 

@user17754849022 Then double check your T4 slips. If the info is correct, then please contact our phone support team for more assistance.