[RESOLVED] “The client and server cannot communicate, because they do not possess a common algorithm”

Should you be running an application like IIS .net Application which need to communicate with an SQL server, you might get the error “The client and server cannot communicate, because they do not possess a common algorithm” when you try to perform a SQL connection.

The issue came up when we had security flags with the TLS versions and made changes to the users workstations registry to avoid the risks which at a later stage we noticed that the users couldn’t open the database files. On the OS TLS 1.0 was disabled for security reasons, however at that moment the used Microsoft SQL server couldn’t communicate with TLS 1.1 or TLS 1.2. So the error message: A connection was successfully established with the server, but then an error occurred during the login process. (provider: SSL Provider, error: 0 – The client and server cannot communicate, because they do not possess a common algorithm.) came up.

After TLS 1.0 was enabled on the affected users workstations the database worked without issues. So make sure that your Microsoft SQL environment is up to date and supports TLS 1.1/1.2 if you wish to disable TLS 1.0.