Event Gateway Error: variable FORM is undefined

Hi,

I recently set up a Filewatcher gateway instance that watches for a file, then based on the file name will perform actions, including deleting the file, in the ONADD function in the associated CFC.

This has worked perfectly for a couple of weeks, however, I noticed a few files in the directory and upon investigation have found it has stopped working.

The error code I'm getting in the EVENTGATEWAY log is:

"Error","Thread-20","04/13/18","12:55:41",,"Error invoking CFC for gateway hrDashboardReportsWatcher: Variable FORM is undefined.  {GATEWAYTYPE={FileWatcher},ORIGINATORID={},CFCMETHOD={onAdd},DATA={{LASTMODIFIED={Fri Apr 13 11:38:31 BST 2018},FILENAME={d:\inetpub\wwwroot\hrdashboard\reportswatcher\114.txt},TYPE={ADD}}},CFCPATH={d:\inetpub\wwwroot\hrdashboard\reportsCode\watchHRDashboardReport.cfc},GATEWAYID={hrDashboardReportsWatcher}}. "

Which seems to indicate that the error is around a variable called form.  But that's the issue.  There is NO variable "form" in any of my code.  In fact, even if i strip out ALL the code apart from the <cffunction name="onAdd" returntype="any"></cffunction>  it still gives me the same error?

Very confused and any help would be appreciated!