Copy-Item Returns IO Exception Invalid Signature From MacOS SMB

Copper Contributor



Currently I'm trying to backup a folder on my MacOS (Mac Mini) to Windows Server. In the middle of the Copy-Item command, process terminated and return error IOException: Invalid Signature.


How can I fix this? Please be kindly advise.


Thanks in advance.

1 Reply



This isn't a PowerShell error.


This is an issue with the MacOS configuration (Linux/SAMBA? - I can't remember) as discussed here:



The proper resolution is to get the MacOS client to supply a signature.


The wildly inappropriate resolution (but obviously still technically possible) is to configured each Windows SMB3-capable machine (be it server or client) to which files may be copied, to disable secure negotiation.