Even with custom submit action I am getting below error
javax.jcr.RepositoryException: org.apache.sling.api.resource.PersistenceException: Resource at '/content/usergenerated/content/forms/af/something/something1/1483510140319_1' is not modifiable.
I am just trying to store the submitted data under a node defined by author and calling " FormsHelper.runAction("/libs/fd/af/components/guidesubmittype/store", "post", resource, slingRequest, slingResponse) " in post.POST.jsp of my custom submit action.
Even the sample code given in above URL throwing same error while submitting the form in my local publish instance.
Have you given any additional permissions to anonymous user to store data