In “5. Residency Obligation - Time Spent Outside Canada”, I encountered the same error message "Your changes cannot be saved. Please try again later." This problem tortured me for a long time, and then Google came here. Thank you for all the suggestions and methods. I got your tips and finally figured out. Although it may be different from what other people encountered, this is one of the reasons why the error occurred. I would like to share it with you. In short, it is a terrible system - it could totally be made friendlier and easier to use.
When the number of characters in this column "Your location(s) during absence (city, country/territory)" is 107, Error! When shortened to 99, ok!
So I guess the character limit for this column should be 99.