User Guide

onError 951
onError
Description
Runs when an uncaught exception occurs in the application.
Syntax
<cffunction name="onError" returnType="void">
<cfargument name="Exception" required=true/>
<cfargument name="EventName" type="String" required=true/>
...
</cffunction>
See also
Method summary, “Handling errors in Application.cfc” in ColdFusion MX Developer’s Guide
Parameters
ColdFusion MX passes the following parameters to the method:
Returns
This method does not return a value; do not use the cfreturn tag.
Usage
Use this method to handle errors in an application-specific manner. This method overrides any
error handlers that you set in the ColdFusion MX Administrator or in
cferror tags. It does not
override try/catch blocks.
Whether the
onError method can display output depends on where the error takes place, as
follows:
• The onError method can display a message to the user if an error occurs during an
onApplicationStart, onSessionStart, onRequestStart, onRequest, or onRequestEnd
event method, or while processing a request.
• The onError method cannot display output to the user if the error occurs during an
onApplicationEnd or onSessionEnd event method, because there is no available page
context; however, it can log an error message.
If the
onError event handler is triggered by a scope-specific event method, such as
onSessionStart, the error prevents further processing at the level of that scope and any lower
scopes. An
onError event triggered by an onSessionStart method, for example, prevents
further processing in the session, but not in the application.
Parameter Description
Exception The ColdFusion MX Exception object. For information on the structure of this object,
see the description of the
cfcatch variable in the cfcatch description.
EventName The name of the event handler that generated the exception. If the error occurs
during request processing and you do not implement an
onRequest method, this is
the empty string.