Action Script - Relevance substitution failed

Can you please assist on checking the below action script, it is failing with the following error

Command failed (Relevance substitution failed)
Command failed (Relevance clauses must be surrounded by { and } guards.)

waithidden expand -f:* “{pathname of client folder of current site & “__Download\windows10.0-kb4462939-x64_68fa7ea1928f909b1497d61c0819aebaf7c37fa8.msu”}” “{pathname of client folder of current site & “__Download"}”
waithidden dism.exe /online /add-package /packagepath:”{pathname of client folder of current site & “__Download\Windows10.0-KB4462939-x64.cab”}" /quiet /norestart /logpath:“{pathname of client folder of current site & “__Download\Windows10.0-KB4462939-x64.log”}”

I didn’t validate your commands, just resolved your syntax

waithidden expand -f:* “{pathname of client folder of current site & “\__Download\windows10.0-kb4462939-x64_68fa7ea1928f909b1497d61c0819aebaf7c37fa8.msu”}” “{pathname of client folder of current site & “__Download”}“

waithidden “{pathname of system folder & “\dism.exe”}” /online /add-package /packagepath:"{pathname of client folder of current site & “\__Download\Windows10.0-KB4462939-x64.log”}”

In a QNA tab the debugger I get this:

q: pathname of client folder of current site & "_Download\Windows10.0-KB4462939-x64.log"
A: C:\Program Files (x86)\BigFix Enterprise\BES Client\__BESData\actionsite_Download\Windows10.0-KB4462939-x64.log

but only if I chose to evaluate using the Local Client Evaluator. That option doesn’t exist for an action tab, so it will always fail in the debugger (there is no current site context for it)

There is an error in your script though - the pathname doesn’t have a ‘\’ on the end so you need to add that in yourself at each point you use it.

Putting it into a simple action does run though:

parameter "x"="{pathname of client folder of current site & "\__Download\Windows10.0-KB4462939-x64.log"}"