This KB article might help. I that is parameter is probe specific. But check step one below too, depending on what you have looked at already.
(1) The first error is noticed when the shell_name reported in the error is not part of the supported shells reported in the same error message (given that this shell is a known one like csh or tcsh), then check the MID Server parameter "mid.ssh.shells_supported" (on the MID server that ran the discovery) where the supported shells are configured. This parameter defines the bourne-compatible shells supported by the MID Server and the default value is "ksh,bash,sh". You can then add your shell to the list.
Please check our documentation for more information on the parameter:
https://docs.servicenow.com/bundle/orlando-servicenow-platform/page/product/mid-server/reference/mid...
(2) This error means that over ssh, the device is not giving a specific shell to use. The action plan here would be to check the discovery user on the remote host and see what shell is specified in its configuration (/etc/passwd) and if there is no shell specified, add one of the supported shells in the file.
NOTE:
There is a probe parameter called "allow_unsupported_shells" which is set on the probe itself and it allows SSH access to commands when a shell is not present on the remote system. This is usually used when discovering a network device without a defined shell. For more information on how and when to use this parameter, kindly refer to our documentation below:
https://docs.servicenow.com/bundle/orlando-it-operations-management/page/product/discovery/reference...
