Why Hongkong preregistration got unsuccessful ?

Hi, if you want to enter HK, you should apply for a HK visa from the China embassy in your country before your trip.

Reason - PAR Hongkong Per-Arrival Registration gets unsuccessful for Indian is your passport place of issue and age. If you are between 18 to 35, then your PAR will be unsuccessful for Kolkata, Hyderabad, Chandigarh, Jalandhar, Nasik, and there are few more.

If its transit flight from Hongkong and not leaving Airport, then PAR is not required.

Solutions -
1. Apply directly with Immigration department, may take atleast 4 weeks.
2. If not going to Hongkong city and going to Macau or any city in China, book a ferry and go.

Note - It is mandatory to give your 'Successful Pre-Arrival Registration' printout on a fresh A4 paper or Ferry booking ticket copy to Airline Check-In, otherwise they will refuse you straight away and not allow to travel. Also, they cancel the ticket (NO REFUND).
In this case, you can Register at the same time (while at check-in counter) on Mobile or Laptop at website - (HK Immigration department) and take a printout from any airline helpdesk counter and travel, as it is just a form and gets approved immediately.