Could not connect to 'hostname': Unknown host.

Make sure that the hostname is a valid host name. You may try to enter the IP address instead of hostname.

Could not connect to 'hostname' (port #): Connection failed.

Make sure that the remote host is ready. Also check if the port number is the one that is used by the remote server.

Unable to initialize WinSock DLL. Make sure that your WinSock is compatible with version 1.1.

This error might happen when your computer has no LAN interface, the network driver or TCP/IP module have not been installed. Check if the Internet connection is working properly before running Xshell.

Failed to create user data folder 'xxx'.

You may not have the permission to create a file in the folder or the disk space may not be enough.

Remote server does not support SSH2 protocol. Continue with SSH1 protocol?

The remote server may support only SSH1 protocol. You need to configure your session to use SSH1.

Failed to compress or decompress outgoing packets.

This message is displayed when a network error occurs or a hostile attacker modifies network data. Try to turn off the zlib compression option in the session properties.

The server sent an unexpected packet. (expected XXX, got YYY)

This error occurs when the packet received is not valid or not supported in the current version of Xshell. For further support, send the error message to our support team.

The server sent an invalid host key.

The host key of the remote server is invalid or has been corrupted. Make sure that the host key is installed correctly in the SSH server.

The MAC (Message Authentication Code) of a packet is incorrect.

This message is displayed when a hostile attacker tries to modify network data. Try using a different encryption algorithm.

The padding size of a packet is incorrect.

The packet has been corrupted during transmission. If the problem persists, there may be an internal error in the SSH client or server.

No matching Cipher, MAC, or Compression algorithm found.

The SSH server doesn't support the algorithms you selected in the session property. Try using other algorithms.

The server rejected the session key.

This may be due to a protocol error in the SSH client or server. Contact the vendor of each program.

The server sent a bad RSA challenge.

This may be due to a protocol error in the SSH client or server. Contact the vendor of each program.

The server sent a disconnect packet. Reason of the problem. (Code: XXX)

This may be caused by many reasons. There may be too many connections to the SSH server, or you may have entered an illegal user name. The exact reason follows the message.

The server rejected a request for user authentication service.

The SSH server does not support user authentication. Xshell cannot connect to this type of server.