I've identified the root cause of one case of this exception. If you always see this exception at the first connection to the database, my solutions may apply to you. 

The 3 possible solutions:
   Solution 1: If SSL is not required. Since it is caused by SSL, we can turn off SSL by appending "SslMode=None" to the connection string.
   Solution 2: If SSL is required, server identity is important and needs to be verified. Connect the server to the internet and try again. 
   Solution 3: If SSL is required but the server identity is not important. Typically SSL is only used to encrypt the network transport in this case. We can turn off CTL update:
1. Press Win+R to open the "Run" dialog 
2. Type "gpedit.msc" (without quotes) and press Enter
3. In the "Local Group Policy Editor", expand "Computer Configuration", expand "Administrative Templates", expand "System", expand "Internet Communication Management", and then click "Internet Communication settings".
4. In the details panel, double-click "Turn off Automatic Root Certificates Update", clickEnabled, then click OK. This change will be effective immediatelly without restart.