Failed to open IdP login page or to test connection with the errors: "HTTP Error 503. The service is unavailable." or "404 - File or directory not found."

Failed to open IdP login page or to test connection with the errors: "HTTP Error 503. The service is unavailable." or "404 - File or directory not found."

Issue: 

When trying to connect to IdP from CPM, you may receive errors:  "HTTP Error 503. The service is unavailable."
 or "404 - File or directory not found." There are no errors in the AD FS event log or  OKTA System logs, as well as CPM logs.


Description:

The issue points to a misconfiguration of identity provider in CPM. "Sign in URL:" option might not be specified properly. 


Resolution:

Go to the general settings on the CPM, and choose an identity provider settings. In the "Sign in URL:"   link should be in the following format for AD FS:

https:// [ADFS server's ip adress or DNS name]/adfs/ls/

for OKTA: 

https://[OKTA hostname]/app/[Application id]/[GUID]/sso/saml