Changepoint does not work when TLS 1.0 is disabled on the server, even if TLS 1.2 is available.
By default, Microsoft .NET 4.5 does not use TLS 1.2 even when available.
Either use .NET 4.6 or apply the following registry change which allows .NET 4.5 to use other encryption methods than only TLS 1.0:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319]
"SchUseStrongCrypto"=dword:00000001
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework\v4.0.30319]
"SchUseStrongCrypto"=dword:00000001
Also, please install general patch 17.02.072.000: User is not able to logon to Changepoint when disable TSL1.0 on the server if the Changepoint database and website were installed on the same server.