[](http://www.uploadify.com) # onError Input Type:**function** Input Format:**function(event,ID,fileObj,errorObj) {}** Required:**optional** The **onError** option allows you to fire a custom function when an error is returned during upload. The default function add the error class to the file queue item. If your custom function returns **false**, the default function will not run. ### Arguments **event **The event object. **ID **The unique identifier of the file that returned an error. **fileObj **An object containing details about the file that was selected. - **[name]** - The name of the file - **[size]** - The size in bytes of the file - **[creationDate]** - The date the file was created - **[modificationDate]** - The last date the file was modified - **[type]** - The file extension beginning with a '.' **errorObj **An object containing details about the error returned. - **[type]** - Either 'HTTP', 'IO', or 'Security' - **[info]** - An error message describing the type of error returned ### Demo Javascript Code 1. $('#file_upload').uploadify({ 1.   'uploader'    : '/uploadify/uploadify.swf', 1.   // Point to a non-existent back-end file so the error always triggers. 1.   'script'      : '/uploadify/uploadify-x.php', 1.   'cancelImg'   : '/uploadify/cancel.png', 1.   'folder'      : '/uploads', 1.   'onError'     : function(event,ID,fileObj,errorObj){ 1.       alert(errorObj.type + ' Error: ' + errorObj.info); 1.     } 1. }); HTML Code 1. <inputtype="file"id="file_upload"name="file_upload"/> 1. <ahref="javascript:$('#file_upload').uploadifyUpload();">Upload Files</a> [Upload Files](#) [](#) Help keep Uploadify free and support the development of other excellent apps!  [home](#)  |  [about](#)  |  [download](#)  |  [demos](#)  |  [documentation](#)  |  [faqs](#)  |  [forums](#) ©2011 by [Reactive Apps](http://www.reactiveapps.com)