If you need urgent help, please contact Aruba Support.
Without information like the firmware version that you use, how you try to upload the certificate, what is the history, it is just guessing what might be the issue. What you may try is to simplify the name of the file that you upload, so if the filename is: controller-cert.my-subdomain.my-domain.com July 2019.pem, try to change it to someting like controller19.pem and try again.