Need help with AngularJS

Hello! I have restored a backup from IONOS backup. After this, my server didn't work anymore. The SSL certificate was gone. Somebody helped me to create a new one. Since then, my server can be accessed again. It has a membership system, and I can still not log in as a member. Somebody told me that port 9000 is not running, and I need to recompile my AngularJS, but I don't know if that is correct. I need somebody to have a look at my server and fix the problem. My website is not really well organized... it uses AngularJS, Socket IO and MySQL. Thank you. Here is a screenshot of what I see when I try to register as a new member on my website: [login to view URL] It used to work before, so I hope it can be resolved relatively easily.