                 Log.error("Error listening on port \(port): \(error). Use server.failed(callback:) to handle")
             }
         }
+        serverLock.unlock()
     }
 
     // MARK: Stop Servers

        server.sslConfig = sslConfig?.config
        server.keepAliveState = keepAliveState
        server.allowPortReuse = allowPortReuse
        httpServersAndPorts.append((server: server, port: port))
        return server
    }


    /// Kitura.start()
    ///```
    public class func start() {
        serverLock.lock()
        for (server, port) in httpServersAndPorts {
            Log.verbose("Starting an HTTP Server on port \(port)...")
            do {
