Hi there @TomacPang!
I can see this is your first post on the PayPal Community Forum, welcome!
I am sorry to hear you are having issues opening up a case via PayPal.
Did you have a case previously opened on this transaction? If not, I would ask that you please try and open a case using the PayPal Website rather than the PayPal App.
I would also recommend clearing the cache and cookies on your browser if this still fails. For the steps on how to open a case, see: How do I open a dispute with a seller? (paypal.com)
If you unfortunately still run into issues, I would suggest reaching out to our customer service team to have this case opened. Please select 'Help' or 'Contact' at the bottom of any PayPal Webpage to get in touch with our customer service team.
I hope this helps! Have a lovely day.
Rebecca.
