Foundation form - "No renderer for extension html, cannot render resource ResourceWrapper" error on submission

Hi,

I'm getting the following error sometimes(not always) on submission of foundation form(cannot use core form component for some reason). Using AEM 6.5.10.

POST /content/xxx/form.html HTTP/1.1] org.apache.sling.servlets.get.impl.DefaultGetServlet No renderer for extension html, cannot render resource ResourceWrapper, type=foundation/components/form/actions/mail, path=/content/xxx/form/jcr:content/content/start, resource=[JcrNodeResource, type=foundation/components/form/start, superType=null, path=/content/xxx/form/jcr:content/content/start]

Similar thread - https://experienceleaguecommunities.adobe.com/t5/adobe-experience-manager/cannot-render-resource-resourcewrapper-error-during-form/m-p/227204#M86975

Apart from the above log, I dont see much in the logs.

Note: The "mail" action has been overlayed and the selector in the following line has been changed. Apart from this, there aren't any changes.

FormsHelper.setForwardPath(slingRequest, resource.getPath() + ".XXXmail.html");

Thank you