Adaptive Form - 'File Attachment' component leads to 'Encountered an internal error while submitting the form' on submit

package com.aem.vk.core.servlets;

import org.apache.commons.io.IOUtils;
import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.SlingHttpServletResponse;
import org.apache.sling.api.resource.Resource;
import org.apache.sling.api.servlets.SlingAllMethodsServlet;
import org.json.JSONException;
import org.json.JSONObject;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Reference;

import javax.jcr.Node;
import javax.jcr.PathNotFoundException;
import javax.jcr.RepositoryException;
import javax.jcr.ValueFormatException;
import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;


@Component(service = Servlet.class, property = { "sling.servlet.methods=get", "sling.servlet.methods=post",
      "sling.servlet.paths=/bin/storeafsubmission" })
public class HandleAdaptiveFormSubmission extends SlingAllMethodsServlet {
   
   //private static final Logger log = LoggerFactory.getLogger(HandleAdaptiveFormSubmission.class);
   private static final long serialVersionUID = 1L;

   @Reference(target = "(&(objectclass=javax.sql.DataSource)(datasource.name=AEM_MYSQL_DB))")
   private DataSource dataSource;

   protected void doPost(SlingHttpServletRequest request, SlingHttpServletResponse response) throws ServletException {
      JSONObject afSubmittedData;
      try {
         afSubmittedData = new JSONObject(request.getParameter("jcr:data"));
         // we will only store the data bound to schema
         JSONObject dataToStore = afSubmittedData.getJSONObject("afData").getJSONObject("afBoundData")
               .getJSONObject("data");
         String formName = afSubmittedData.getJSONObject("afData").getJSONObject("afSubmissionInfo")
               .getString("afPath");
         //log.debug("The form name is " + formName);
         insertData(dataToStore, formName);

      } catch (JSONException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      } catch (ClassNotFoundException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      } catch (SQLException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      }

   }

   public void insertData(org.json.JSONObject jsonData, String formName) throws ClassNotFoundException, SQLException {
      //log.debug("The json object I got to insert was " + jsonData.toString());
      String insertTableSQL = "INSERT INTO db_vk.formsubmissions(formdata,formname) VALUES(?,?)";
      //log.debug("The query is " + insertTableSQL);
      Connection c = getConnection();
      //Connection c = getConn();
      PreparedStatement pstmt = null;
      try {
         pstmt = null;
         pstmt = c.prepareStatement(insertTableSQL);
         pstmt.setString(1, jsonData.toString());
         pstmt.setString(2, formName);
         //log.debug("Executing the insert statment  " + pstmt.executeUpdate());
         pstmt.executeUpdate();
         c.commit();
      } catch (SQLException e) {

         //log.error("Getting errors", e);
      } finally {
         if (pstmt != null) {
            try {
               pstmt.close();
            } catch (SQLException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
            }
         }
         if (c != null) {
            try {
               c.close();
            } catch (SQLException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
            }
         }
      }
   }

   public Connection getConnection() {
      //log.debug("Getting Connection ");
      Connection con = null;
      try {

         con = dataSource.getConnection();
      // log.debug("got connection");
         return con;
      } catch (Exception e) {
      // log.error("not able to get connection ", e);
      }
      return null;
   }

   public String getJSONSchema(String afPath) {
      // TODO Auto-generated method stub
      afPath = afPath.replaceAll("/content/dam/formsanddocuments/", "/content/forms/af/");
      Resource afResource = getResolver.getServiceResolver().getResource(afPath + "/jcr:content/guideContainer");
      Node resNode = afResource.adaptTo(Node.class);
      String schemaNode = null;
      try {
         schemaNode = resNode.getProperty("schemaRef").getString();
      } catch (ValueFormatException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      } catch (PathNotFoundException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      } catch (RepositoryException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      }
      if (schemaNode.startsWith("/content/dam")) {
         //log.debug("The schema is in the dam");
         afResource = getResolver.getServiceResolver()
               .getResource(schemaNode + "/jcr:content/renditions/original/jcr:content");
         resNode = afResource.adaptTo(Node.class);
         InputStream jsonSchemaStream = null;
         try {
            jsonSchemaStream = resNode.getProperty("jcr:data").getBinary().getStream();
            Charset charset = StandardCharsets.UTF_8;
            String jasonSchemaString = IOUtils.toString(jsonSchemaStream, charset);
            //log.debug("The Schema is " + jasonSchemaString);
            return jasonSchemaString;
         } catch (ValueFormatException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
         } catch (PathNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
         } catch (RepositoryException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
         } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
         }
      }
      if (schemaNode.startsWith("/assets")) {
         afResource = getResolver.getServiceResolver()
               .getResource(afPath + "/jcr:content/guideContainer/" + schemaNode + "/jcr:content");
         resNode = afResource.adaptTo(Node.class);
         InputStream jsonSchemaStream = null;
         try {
            jsonSchemaStream = resNode.getProperty("jcr:data").getBinary().getStream();
            Charset charset = StandardCharsets.UTF_8;
            String jasonSchemaString = IOUtils.toString(jsonSchemaStream, charset);
            //log.debug("The Schema is " + jasonSchemaString);
            return jasonSchemaString;
         } catch (ValueFormatException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
         } catch (PathNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
         } catch (RepositoryException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
         } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
         }
      }
      return null;
   }

}

Can you please try using custom submit qction

https://experienceleague.adobe.com/docs/experience-manager-learn/forms/adaptive-forms/custom-submit-aem-forms-article.html?lang=en

@rakesh443 

Thanks for confirming! It's the same issue wherein the target host is missing.

1. Can you provide the complete URL in the endpoint - http://host:port/path_to_rest_end_point and 

2. Exclude the path_to_rest_end_point from the authentication requirement under the "Sling authentication service" under http://host:port/system/console/configMgr

Hope this helps!