Access check violations within custom Lightning (Aura) components are strictly enforced in Salesforce Experience Builder (formerly Community Builder). When a Lightning component attempts to access an attribute, method, or property that violates access check rules, the page may display an error or fail to load. This article explains the common error messages you can encounter and how to fix them.
When a Lightning component has an access check violation, users in the Experience Builder preview or published community may see messages such as:
Action failed: c$CloudCrazeComponent$cntroller$getHost [Cannot read property 'Qb' of undefined]
Something has gone wrong. Error in $A.getCallback() [Cannot read property 'Qb' of undefined]
Failling descriptor: {markup://c:CloudCrazeTopicRelatedProducts}. Please try again.
Action failed: c$CloudCrazeComponent$cntroller$getHost [Cannot read property '$getTypeDefDescriptor$' of undefined]
Something has gone wrong. Error in $A.getCallback() [Cannot read property '$getTypeDefDescriptor$' of undefined]
Failling descriptor: {markup://c:CloudCrazeTopicRelatedProducts}. Please try again.
Lightning Component debug mode disabled: If the page contains custom Lightning components with access check errors, the page may or may not display depending on which component has failed and where it is located. In situations where the error page is not displayed, the rest of the page will still render with the exception of the failing component.
Lightning Component debug mode enabled: The user will not be redirected to the error page. Instead, they will see an infinite loading indicator or the page may fail to load entirely. If the browser's developer tools are open, access check errors for the components will be visible in the console output.
Sample Experience Builder errors
The first step is to identify the component that is causing the issue. Look at the error message dialog and note the component name. For example, in the error "Action failed: c$CloudCrazeComponent$controller$getHost [Cannot read property '$getTypeDefDescriptor$' of undefined]," the component is c:CloudCrazeComponent and the issue is in the getHost() function within the controller JavaScript file.
Once you have identified the component, open it in the Developer Console and analyze the code. Follow the guidelines in the "Fixing Access Check Errors" section in the Salesforce Controlling Access developer documentation to resolve the access check violations, then save the changes. Reload Community Builder and access the page that was throwing the error to confirm the error no longer appears.
A frequent cause of this error is an Aura component's controller or helper JavaScript file attempting to call component.set() or component.get() on an attribute that has not been declared in the component markup. For example, if the controller calls component.set("v.someAttribute", "someValue") but the component markup does not include an aura:attribute declaration with the name "someAttribute", the access check error will occur because the component is trying to set a value on an attribute that does not exist in the component's attribute schema.
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