Q: What causes GlideAjax Call Not Returning Data in ServiceNow?

Script Include not marked as client callable — Navigate to System Definition > Script Includes and open your Script Include record. Check if the 'Client callable' checkbox is unchecked. This is the most common cause of null callbacks. Method name mismatch in sysparm_name parameter — Compare the method name in your addParam('sysparm_name', 'methodName') call against the actual function name in the Script Include. Names are case-sensitive and must match exactly. Script Include method not calling this.setAnswer() — Check your Script Include method implementation. The method must call this.setAnswer(value) or this.setAnswer(JSON.stringify(object)) to return data to the callback function. Script Include class name doesn't match file name — Verify the Script Include record name matches exactly with the class name in addGlideAjax('ClassName'). Case sensitivity matters - 'MyUtils' is different from 'myutils'. Server-side JavaScript error in Script Include — Check System Logs > System Log > All for JavaScript errors occurring when your GlideAjax call executes. Filter by your Script Include name or method name to find relevant errors. Missing prototype extension or incorrect method structure — Verify your Script Include method is defined as ClassName.prototype.methodName = function() and the Script Include extends AbstractAjaxProcessor if using the older pattern.

Question 1

What causes GlideAjax Call Not Returning Data in ServiceNow?

Accepted Answer

Script Include not marked as client callablehigh likelihood

Navigate to System Definition > Script Includes and open your Script Include record. Check if the 'Client callable' checkbox is unchecked. This is the most common cause of null callbacks.

Method name mismatch in sysparm_name parameterhigh likelihood

Compare the method name in your addParam('sysparm_name', 'methodName') call against the actual function name in the Script Include. Names are case-sensitive and must match exactly.

Script Include method not calling this.setAnswer()high likelihood

Check your Script Include method implementation. The method must call this.setAnswer(value) or this.setAnswer(JSON.stringify(object)) to return data to the callback function.

Script Include class name doesn't match file namemedium likelihood

Verify the Script Include record name matches exactly with the class name in addGlideAjax('ClassName'). Case sensitivity matters - 'MyUtils' is different from 'myutils'.

Server-side JavaScript error in Script Includemedium likelihood

Check System Logs > System Log > All for JavaScript errors occurring when your GlideAjax call executes. Filter by your Script Include name or method name to find relevant errors.

Missing prototype extension or incorrect method structurelow likelihood

Verify your Script Include method is defined as ClassName.prototype.methodName = function() and the Script Include extends AbstractAjaxProcessor if using the older pattern.

Question 2

How do you fix GlideAjax Call Not Returning Data in ServiceNow?

Accepted Answer

How to fix it Navigate to System Definition > Script Includes and open your Script Include record. Check the Client callable checkbox. If unchecked, check it and click Update. This makes the Script Include accessible from client-side code. Verify the Script Include Name field exactly matches what you use in new GlideAjax('ScriptIncludeName'). Case matters. In the Script Include code, ensure your method calls this.setAnswer(returnValue) to send data back to the callback. Check that the method name in addParam('sysparm_name', 'methodName') exactly matches a function in your Script Include. Navigate to System Logs > System Log > All and filter by your Script Include name to check for JavaScript errors. If using the traditional pattern, ensure your Script Include extends AbstractAjaxProcessor and methods are defined as ClassName.prototype.methodName = function(). Test your fix by refreshing the form and triggering the GlideAjax call again. If returning objects or arrays, use this.setAnswer(JSON.stringify(myObject)) in the Script Include and JSON.parse(answer) in the callback. Clear your browser cache if the Script Include was recently modified, as ServiceNow may cache the old version.

Question 3

How do you prevent GlideAjax Call Not Returning Data in ServiceNow?

Accepted Answer

Always check the 'Client callable' checkbox when creating Script Includes that will be called from client scripts. Use consistent naming conventions for Script Include names and method names, and document the exact case sensitivity requirements. Create a standard Script Include template that includes proper error handling and logging to catch issues early. Test GlideAjax calls in the browser console first using the same parameters to verify the Script Include responds correctly. Add validation in your Script Include methods to ensure required parameters are present before processing and returning data.

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