Hello,
1. If a user does not complete the registration form properly where custom fields are needed, in tab view, the user does not know there is an error if the incomplete field is not the active tab. The tab itself containing the incomplete field should be turn red for example
2. The avatar and file upload is problematic if un supported file type or if the file size threshold for the server is exceeded. Since ajax or something similar is no used, the file type and size is only compared after the page load. In my testing, I tried to upload a purposely large file and there was no error. The form saved but the image did not and no error appeared.
Jordan