diff --git a/lib/actions/addOwnedBy.js b/lib/actions/addOwnedBy.js
index b4c75671..47024dce 100644
--- a/lib/actions/addOwnedBy.js
+++ b/lib/actions/addOwnedBy.js
@@ -4,10 +4,20 @@ const config = require('../config')
 const getOwnedBy = require('../query/ownedBy')
 const retrieveUris = require('../retrieveUris')
 const getUrisFromReq = require('../getUrisFromReq')
+const db = require('../db')
 
-module.exports = function (req, res) {
+module.exports = async function (req, res) {
   const userUri = req.body.user
 
+  var userId = ''
+  if (req.body.user.lastIndexOf('/') >= 0) {
+    userId = req.body.user.substring(req.body.user.lastIndexOf('/') + 1)
+  }
+
+  const user = await db.model.User.findOne({
+    where: db.sequelize.or({ email: userId }, { username: userId })
+  })
+
   const { graphUri, uri } = getUrisFromReq(req, res)
 
   const sharedAdditionQuery = loadTemplate('./sparql/AddToSharedCollection.sparql', {
@@ -23,6 +33,12 @@ module.exports = function (req, res) {
       })
     }
 
+    if (!user) {
+      return new Promise(function (resolve, reject) {
+        reject(new Error('user ' + userId + ' not recognized'))
+      })
+    }
+
     return sparql.updateQuery(sharedAdditionQuery, userUri).then(() => {
       return retrieveUris(uri, graphUri)
     }).then((uris) => {
diff --git a/lib/actions/removeOwnedBy.js b/lib/actions/removeOwnedBy.js
index 9795a27c..253fa4ec 100644
--- a/lib/actions/removeOwnedBy.js
+++ b/lib/actions/removeOwnedBy.js
@@ -6,7 +6,7 @@ const loadTemplate = require('../loadTemplate')
 const getOwnedBy = require('../query/ownedBy')
 
 module.exports = function (req, res) {
-  const { graphUri, uri, share } = getUrisFromReq(req, res)
+  const { graphUri, uri, url } = getUrisFromReq(req, res)
 
   return getOwnedBy(uri, graphUri).then((ownedBy) => {
     if (ownedBy.indexOf(config.get('databasePrefix') + 'user/' + req.user.username) === -1) {
@@ -46,7 +46,11 @@ module.exports = function (req, res) {
         })
         .then(() => {
           // Redirect only once after all promises resolve
-          res.redirect(share)
+          if (!req.accepts('text/html')) {
+            res.status(200).send('Success')
+          } else {
+            res.redirect(url)
+          }
         })
         .catch((err) => {
           console.error('Error:', err)
diff --git a/lib/views/addOwner.js b/lib/views/addOwner.js
index 51ef4e2c..9508582d 100644
--- a/lib/views/addOwner.js
+++ b/lib/views/addOwner.js
@@ -14,9 +14,7 @@ module.exports = function (req, res) {
 
 function view (req, res) {
   const {
-    graphUri,
-    uri,
-    designId
+    uri
   } = getUrisFromReq(req, res)
 
   db.model.User.findAll().then(users => {
@@ -33,14 +31,22 @@ function view (req, res) {
 
 function post (req, res) {
   addOwnedBy(req, res).then(() => {
-    res.redirect(req.originalUrl.replace('/addOwner', ''))
+    if (!req.accepts('text/html')) {
+      res.status(200).send('Success')
+    } else {
+      res.redirect(req.originalUrl.replace('/addOwner', ''))
+    }
   }, function (err) {
-    const locals = {
-      config: config.get(),
-      section: 'errors',
-      user: req.user,
-      errors: [ err ]
+    if (!req.accepts('text/html')) {
+      res.status(400).send(err.message)
+    } else {
+      const locals = {
+        config: config.get(),
+        section: 'errors',
+        user: req.user,
+        errors: [ err ]
+      }
+      res.send(pug.renderFile('templates/views/errors/errors.jade', locals))
     }
-    res.send(pug.renderFile('templates/views/errors/errors.jade', locals))
   })
 }