I was trying to log-on to Dynamic 365 CRM v9.0 from Internet Explorer and getting below error page.
This is because Microsoft is enforcing TLS 1.2 protocol when accessing Dynamics 365 v9.0
As this error message clearly mentioned that one is to edit Internet explorer setting.
I am explaining what exactly needed to be done.
1) Open the Internet Explorer setting. Go to Tools > Internet Options.
2) Go to Tab Advanced and scroll down and look for heading Security.
3)Under heading Security, look for Use TLS 1.2, check the box as depicted in below image.
Try accessing CRM and I hope without any further error, CRM will be accessible.
From a coding perspective if any application is trying to access Dynamic 365 v9.0 we need to invoke below commands to ensure that application is making use of TLS protocol 1.2.
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
Other blogs for more details references are
I hope this will save a lot of time.