Element 1 is undefined in a Java object of type class coldfusion.runtime.Array

[nkostic]

My users are lately getting this error:

Element 1 is undefined in a Java object of type class coldfusion.runtime.Array
Error occured in client.cfc: line 268
Called from client.cfc line 283
Called from client.cfc line 268
Called from client.cfc line 283
Called from client.cfc line 283
Called from client.cfc line 196
Called from client.cfc line 136
Called from application.cfc line ...

Application is running on ColdFusion10