Week 1 - Optional Lab notebooks - Not able to access any of the optional lab notes books from week 1. anyone there who came across the same issue and resolved it?

Please see this thread:

I have been facing same problem since tomorrow evening. It shows the error message like “We were unable to retrieve a launch URL. Please make sure you are logged in to Coursera, and have access to this lab”. I have faced the same issue 2 week back but solved it automatically.
Please help…