Add more info to encryption related connection failures

src/SqlAsyncCollector.cs

@@ -95,7 +95,7 @@ public SqlAsyncCollector(IConfiguration configuration, SqlAttribute attribute, I
             using (SqlConnection connection = BuildConnection(attribute.ConnectionStringSetting, configuration))
             {
                 this._logger.LogDebugWithThreadId("BEGIN OpenSqlAsyncCollectorVerifyDatabaseSupportedConnection");
-                connection.Open();
+                connection.OpenAsyncWithSqlErrorHandling(CancellationToken.None).Wait();
                 this._logger.LogDebugWithThreadId("END OpenSqlAsyncCollectorVerifyDatabaseSupportedConnection");
                 VerifyDatabaseSupported(connection, logger, CancellationToken.None).Wait();
             }

src/SqlBindingUtilities.cs

@@ -203,5 +203,35 @@ public static async Task VerifyDatabaseSupported(SqlConnection connection, ILogg
                 }
             }
         }
+
+        /// <summary>
+        /// Opens a connection and handles some specific errors if they occur.
+        /// </summary>
+        /// <param name="connection">The connection to open</param>
+        /// <param name="cancellationToken">The cancellation token to pass to the OpenAsync call</param>
+        /// <returns>The task that will be completed when the connection is made</returns>
+        /// <exception cref="InvalidOperationException">Thrown if an error occurred that we want to wrap with more information</exception>
+        internal static async Task OpenAsyncWithSqlErrorHandling(this SqlConnection connection, CancellationToken cancellationToken)
+        {
+            try
+            {
+                await connection.OpenAsync(cancellationToken);
+            }
+            catch (Exception e)
+            {
+                SqlException sqlEx = e is AggregateException a ? a.InnerExceptions.OfType<SqlException>().First() :
+                    e is SqlException s ? s :
+                    null;
+                // Error number for:
+                //  A connection was successfully established with the server, but then an error occurred during the login process.
+                //  The certificate chain was issued by an authority that is not trusted.
+                // Add on some more information to help the user figure out how to solve it
+                if (sqlEx?.Number == -2146893019)
+                {
+                    throw new InvalidOperationException("The default values for encryption on connections have been changed, please review your configuration to ensure you have the correct values for your server. See https://aka.ms/afsqlext-connection for more details.", e);
+                }
+                throw;
+            }
+        }
     }
 }

src/SqlConverters.cs

@@ -180,7 +180,7 @@ public virtual async Task<string> BuildItemFromAttributeAsync(SqlAttribute attri
                 {
                     adapter.SelectCommand = command;
                     this._logger.LogDebugWithThreadId("BEGIN OpenBuildItemFromAttributeAsyncConnection");
-                    await connection.OpenAsync();
+                    await connection.OpenAsyncWithSqlErrorHandling(CancellationToken.None);
                     this._logger.LogDebugWithThreadId("END OpenBuildItemFromAttributeAsyncConnection");
                     Dictionary<TelemetryPropertyName, string> props = connection.AsConnectionProps();
                     TelemetryInstance.TrackConvert(type, props);

src/TriggerBinding/SqlTriggerListener.cs

@@ -122,7 +122,7 @@ public async Task StartAsync(CancellationToken cancellationToken)
                 using (var connection = new SqlConnection(this._connectionString))
                 {
                     this._logger.LogDebugWithThreadId("BEGIN OpenListenerConnection");
-                    await connection.OpenAsync(cancellationToken);
+                    await connection.OpenAsyncWithSqlErrorHandling(cancellationToken);
                     this._logger.LogDebugWithThreadId("END OpenListenerConnection");
                     this._telemetryProps.AddConnectionProps(connection);