Hi,
from my experience, in this type of cases I do:
copy new config which vmanage wants to push to the device.
Do ssh to device and do manual config. After commit, if something is wrong device CLI gives error/warning message (many times, more detailed info than vmanage gives in case of config push failure). When config is OK, CLI just notifies that system is vmanaged and config should be done via vmanage.
HTH,
HTH,
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