Fencing fails in a RHEL 5 or 6 High Availability cluster with a traceback and error "TypeError: can only concatenate list (not 'str') to list"

Solution Unverified - Updated -


  • An error occurs when getting the status with fencing agent fence_bladecenter:
2015-02-12 12:11:30 -07:00 Thu node42 [user.info] abrt: detected unhandled Python exception in '/usr/sbin/fence_bladecenter'
  • A python exception is thrown when the fencing agent fence_bladecenter tries to get status and abrt catches it:
fencing.py:952:fence_login:TypeError: can only concatenate list (not "str") to list

Traceback (most recent call last):
  File "/usr/sbin/fence_bladecenter", line 143, in <module>
  File "/usr/sbin/fence_bladecenter", line 126, in main
    conn = fence_login(options, "(username: )")
  File "/usr/share/fence/fencing.py", line 952, in fence_login
    result = conn.log_expect(options, [ "Enter passphrase for key '"+options["-k"]+"':", "Are you sure you want to continue connecting (yes/no)?" ] + options["-c"], int(options["-y"]))
TypeError: can only concatenate list (not "str") to list
  • Fencing is failing in my cluster after updating to RHEL 5 Update 11
  • Fencing is failing in my cluster after updating to RHEL 6 Update 5
  • fence_virt doesn't work, and testing it on the command line gives a traceback and exception


  • Red Hat Enterprise Linux (RHEL) 5 and 6 with the High Availability Add On
  • RHEL 6: fence-agents-3.1.5-48.el5 or later
  • RHEL 5: cman-2.0.115-124.el5 or later
  • Any of the following fence-agents configured in a fencedevice in /etc/cluster/cluster.conf:
    • fence_apc
    • fence_bladecenter
    • fence_brocade
    • fence_drac5
    • fence_hpblade
    • fence_ilo_mp
    • fence_rsa
    • fence_rsb
    • fence_virsh
    • fence_vmware
    • fence_wti
  • The fencedevice configured with one of the above agents has an identity_file specified in its attributes

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