rdiff-backup differnet versions over ssh compleatly fails

[Renatas Ulevicius Lexita, UAB]

Backup server:
Ubuntu 18.04.4 LTS 64 bit
rdiff-backup version 1.2.8

remote machine 192.168.2.100
Ubuntu 20.04 LTS 64 bit
rdiff-backup version 2.0.4

From *backup server* i execute following command

rdiff-backup -v9 --force root@192.168.2.100::/files /backup/files

Wed Jun 24 10:59:29 2020 Using rdiff-backup version 1.2.8
Wed Jun 24 10:59:29 2020 Executing ssh -C root@192.168.2.100 rdiff-backup --server
Wed Jun 24 10:59:29 2020 Client sending (0): ConnectionRequest: Globals.get with 1 arguments
Wed Jun 24 10:59:29 2020 Client sending (0): 'version'
root@192.168.2.100's password:
Wed Jun 24 10:59:33 2020 Client received (0): 'version'
Wed Jun 24 10:59:33 2020 Exception ''version'' raised of class '<type 'exceptions.KeyError'>':
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/Main.py", line 304, in error_check_Main
    try: Main(arglist)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/Main.py", line 321, in Main
    rps = map(SetConnections.cmdpair2rp, cmdpairs)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/SetConnections.py", line 76, in cmdpair2rp
    if cmd: conn = init_connection(cmd)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/SetConnections.py", line 152, in init_connection
    check_connection_version(conn, remote_cmd)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/SetConnections.py", line 160, in check_connection_version
    try: remote_version = conn.Globals.get('version')
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/connection.py", line 450, in __call__
    return apply(self.connection.reval, (self.name,) + args)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/connection.py", line 370, in reval
    if isinstance(result, Exception): raise result

Traceback (most recent call last):
  File "/usr/bin/rdiff-backup", line 30, in <module>
    rdiff_backup.Main.error_check_Main(sys.argv[1:])
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/Main.py", line 304, in error_check_Main
    try: Main(arglist)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/Main.py", line 321, in Main
    rps = map(SetConnections.cmdpair2rp, cmdpairs)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/SetConnections.py", line 76, in cmdpair2rp
    if cmd: conn = init_connection(cmd)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/SetConnections.py", line 152, in init_connection
    check_connection_version(conn, remote_cmd)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/SetConnections.py", line 160, in check_connection_version
    try: remote_version = conn.Globals.get('version')
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/connection.py", line 450, in __call__
    return apply(self.connection.reval, (self.name,) + args)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/connection.py", line 370, in reval
    if isinstance(result, Exception): raise result
KeyError: 'version'
Fatal Error: Lost connection to the remote system

When I try to run manually command on *backup server* to test how its works

rdiff-backup -v9 --server
Wed Jun 24 11:00:59 2020 Using rdiff-backup version 1.2.8
Wed Jun 24 11:00:59 2020 Starting server

on *remote mashine*
rdiff-backup -v9 --server

Command is running- but there is no output

[Renatas Ulevicius Lexita, UAB (lexita)]

Also i try oposite direction

From *192.168.2.100* i want to copy to *backup server*

rdiff-backup -v9 /files root@192.168.2.200::/backup/files

Exception 'object.__new__(X): X is not a type object (classobj)' raised of class '<type 'exceptions.TypeError'>':
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/Main.py", line 304, in error_check_Main
    try: Main(arglist)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/Main.py", line 324, in Main
    take_action(rps)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/Main.py", line 278, in take_action
    connection.PipeConnection(sys.stdin, sys.stdout).Server()
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/connection.py", line 355, in Server
    self.get_response(-1)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/connection.py", line 315, in get_response
    try: req_num, object = self._get()
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/connection.py", line 241, in _get
    if format_string == "o": result = cPickle.loads(data)
  File "/usr/lib/python2.7/copy_reg.py", line 48, in _reconstructor
    obj = object.__new__(cls)

Traceback (most recent call last):
  File "/usr/bin/rdiff-backup", line 30, in <module>
    rdiff_backup.Main.error_check_Main(sys.argv[1:])
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/Main.py", line 304, in error_check_Main
    try: Main(arglist)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/Main.py", line 324, in Main
    take_action(rps)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/Main.py", line 278, in take_action
    connection.PipeConnection(sys.stdin, sys.stdout).Server()
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/connection.py", line 355, in Server
    self.get_response(-1)
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/connection.py", line 315, in get_response
    try: req_num, object = self._get()
  File "/usr/lib/python2.7/dist-packages/rdiff_backup/connection.py", line 241, in _get
    if format_string == "o": result = cPickle.loads(data)
  File "/usr/lib/python2.7/copy_reg.py", line 48, in _reconstructor
    obj = object.__new__(cls)
TypeError: object.__new__(X): X is not a type object (classobj)
2020-06-24 16:13:31.904701 +0300 <CLIENT-868713> Fatal Error: Truncated header string (problem probably originated remotely)

Couldn't start up the remote connection by executing

    ssh -C root@192.168.2.200 rdiff-backup --server

Remember that, under the default settings, rdiff-backup must be
installed in the PATH on the remote system. See the man page for more
information on this. This message may also be displayed if the remote
version of rdiff-backup is quite different from the local version (2.0.4.dev9+g026aac2.ubuntu20.4.1).

[Otto Kekäläinen (otto)]

You could read the README https://github.com/rdiff-backup/rdiff-backup on how to install rdiff-backup 2.0 on both hosts to avoid version mismatch issues, as they at least are one source of issues.