EXSLT error : XPath exception - Extension function not found: parse-date

date:parse-date definition:

string date:parse-date(string, string)

XPath you’re requesting when compiled ends up by searching for following function

string date:parse-date(nodeSet, string)

and thus can’t be found.

The solution is to force the first argument of the function to string as well. This can be done with AS:NodeToString.

AS:LookupValue(
    '8f623352-bfaf-4e7a-bf56-1e9be280ca96', 
    'OnWay_par_DumpId', 
    /ROOT/dumpId,
    'OnWay_parFleetVehicleIdId',
    /ROOT/loaderId,
    'OnWay_parLoadTimeStart',
    date:parse-date(AS:NodeToString(/ROOT/timeStart), 'yyyyMMddHHmmss'))

There are no plans to adjust this behaviour.