Entering an invalid format for the Subject Alternative Name parameter while creating a self-signed certificate in Portal for ArcGIS does not return an error, and the certificate is not created.

Workaround

1. Navigate to the Portal for ArcGIS Admin page.
2. Navigate to Home > Security > SSLCertificates > Generate.
3. Enter all the parameters, including 'Subject Alternative Name', using the following format to successfully generate the certificate:

SAN=DNS:DNS name, IP:IP address. (as mentioned in the following document, http://server.arcgis.com/en/portal/latest/administer/windows/import-a-certificate-into-the-portal.htm#ESRI_SECTION1_31E574D0346C4DF1BBC9EDECE722A8F4).

Steps to Reproduce