There is a workaround that fixed the problem for me. It was obviously related to `python-paramiko`.
1. Remove the `python-paramiko` package instelled w/ apt: `apt remove python-paramiko` 2. Install paramiko via pip that provides a newer obviously fixed version: `apt install duplicity python-pip -y` `pip install paramiko` -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to duplicity in Ubuntu. https://bugs.launchpad.net/bugs/1665643 Title: Duplicity error "ssh: Unknown exception: CTR mode needs counter parameter, not IV" Status in duplicity package in Ubuntu: Confirmed Bug description: Ubuntu 16.04 - Duplicity Following error using duplicity with SFTP backend after upgrade today on several machines. Confirmed to be an upgrade as had a working machine, apt upgraded it, then it was broken. Only packages I can see that were upgraded that might be related are python-crypto (2.6.1-6ubuntu0.16.04.1) and libssh2-1:amd64 (1.5.0-2ubuntu0.1). IMPORTANT: Duplicity unusable in SFTP mode since the upgrade, it is not possible to perform backups. ssh: Unknown exception: CTR mode needs counter parameter, not IV ssh: Traceback (most recent call last): ssh: File "/usr/lib/python2.7/dist-packages/paramiko/transport.py", line 1744, in run ssh: self.kex_engine.parse_next(ptype, m) ssh: File "/usr/lib/python2.7/dist-packages/paramiko/kex_group1.py", line 75, in parse_next ssh: return self._parse_kexdh_reply(m) ssh: File "/usr/lib/python2.7/dist-packages/paramiko/kex_group1.py", line 112, in _parse_kexdh_reply ssh: self.transport._activate_outbound() ssh: File "/usr/lib/python2.7/dist-packages/paramiko/transport.py", line 2074, in _activate_outbound ssh: engine = self._get_cipher(self.local_cipher, key_out, IV_out) ssh: File "/usr/lib/python2.7/dist-packages/paramiko/transport.py", line 1649, in _get_cipher ssh: return self._cipher_info[name]['class'].new(key, self._cipher_info[name]['mode'], iv, counter) ssh: File "/usr/lib/python2.7/dist-packages/Crypto/Cipher/AES.py", line 94, in new ssh: return AESCipher(key, *args, **kwargs) ssh: File "/usr/lib/python2.7/dist-packages/Crypto/Cipher/AES.py", line 59, in __init__ ssh: blockalgo.BlockAlgo.__init__(self, _AES, key, *args, **kwargs) ssh: File "/usr/lib/python2.7/dist-packages/Crypto/Cipher/blockalgo.py", line 141, in __init__ ssh: self._cipher = factory.new(key, *args, **kwargs) ssh: ValueError: CTR mode needs counter parameter, not IV ssh: BackendException: ssh connection to cli-5l...@sftp.orbit.brightbox.com:22 failed: CTR mode needs counter parameter, not IV ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: duplicity 0.7.06-2ubuntu2 ProcVersionSignature: Ubuntu 4.4.0-62.83-generic 4.4.40 Uname: Linux 4.4.0-62-generic x86_64 ApportVersion: 2.20.1-0ubuntu2.5 Architecture: amd64 CurrentDesktop: Unity Date: Fri Feb 17 14:03:00 2017 InstallationDate: Installed on 2016-06-03 (259 days ago) InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1) SourcePackage: duplicity UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/duplicity/+bug/1665643/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp