Yes, updation of date of exit of previous job/employment is mandatory for applying online transfer. The date of exit can be updated only after two months of leaving a job. Also, the date of exit can be any date in the month in which the last contribution was made by the previous employer.
The facility is based on Aadhaar-based one-time password (OTP). Thus, it can only be utilized by those who have activated their UAN and linked their UAN with a verified Aadhaar number and have a mobile linked to Aadhaar for receiving the OTP sent for verification.