Proof of claimed work experience is mandatory for CEC as well if you're claiming points for that. Work reference letters are required by OOPNP and other provincial programs as well.
There are workarounds available - not every organization is going to provide reference letters for CIC. Get your ex-colleagues/ex-supervisor to sign a "To whoever this may concern" type declaration that you prepare which has everything CIC needs on a reference letter. Include all the details about your employment including company name/contact/URL, designation, roles & responsibilities, tenure of employment, supervisor name/designation/contact details, working hours/week, full-time employment and salary details. Collect their business card as well. Get this declaration notarized and upload it and the business card along with a nicely drafted LOE that highlights your unsuccessful efforts at obtaining a reference letter in the required format from your employer because they have shut shop and politely requests the officer to consider your application as complete and process the same on its merits. Add any other supporting document including pay stubs, job offer letter etc to reinforce the declaration. Inform your ex-colleagues/ex-supervisor to possibly expect a call from CIC (unlikely to happen with everyone but they do call if they doubt the legitimacy of employment).
If your ex-colleagues/ex-supervisor refuse to sign such a declaration, sign it yourself as a last resort and make it sound like a self declaration, get it notarized and upload along with an LOE that highlights your unsuccessful attempts at getting such a letter from even your ex-colleagues/ex-supervisor and politely request the officer to consider your application as complete in all respects.
All the best!
