Try this: Go to the Summary page where your T4E is listed. Answer YES to the question "Did XXX received EI...".  Answering YES will prompt a question about the amount received: leave this amount at $0 (very important). Save. Following this, I was able to submit my tax report to the CRA electronically.

If you have a RL-6 :  

Removed the amount in Box A of Relevé 6. You will still have the amount in your QC forms. 

If you don't have a RL-6: 

In the T4E summary page (the next page after you enter your T4E information) > answer No to the question "Did you receive employment insurance maternity or parental benefits in?". 

If you have already answered Yes and added your total amount > You need to go back, change this amount to $0 first then change the answer No. If you change the answer to No without reducing the amount to $0 first, you will still get the error.  

I hope this was helpful