@Er84-363047 Is this issue resolved for you? Were you able to Netfile? 

Hello,   I tried to make some changes a few days ago and the results were the same. 
I will attempt again at my earliest conveniences.  
I have already paid for the return, will that affect my ability to reenter T-slips and get a corrected return? 
thank you 

Unfortunately no.  The preview stills shows a negative number in a place the number should be converted to a zero.  

@Er84-363047 Is it possible for you to give us the exact error message? or send a screenshot (make sure to hide all personal info showing on the screenshot)?

Can you please give us more details about the return? which T-Slips? type of incomes? 

Any information that can help us find a solution.

Thank you for choosing TurboTax.