There’s an easy fix to the issue:
Cannot serve request to /content/forms/af/formwithattachments/jcr:content/guideContainer.af.submit.jsp in com.adobe.aemds.guide.servlet.GuideSubmitServlet
- Make sure AEM isn’t running.
- Open your sling.properties file under \crx-quickstart\conf\ with Brackets or equivalent good editor.
- Add the following properties to the sling.properties file
- Save and start your server.
Take note that if this step was not taken care of as part of your AEM / Forms installation, you may want to review all of the steps in the configuration guide. It is likely things like PDFg are not setup.