Index: lams_admin/src/java/org/lamsfoundation/lams/admin/web/controller/UserOrgSaveController.java
===================================================================
diff -u -r063b75b0ad3ad6365af21a3f77a82700f1bfdc5f -r064661349150076f41ef249b55b054a72f6a3fb5
--- lams_admin/src/java/org/lamsfoundation/lams/admin/web/controller/UserOrgSaveController.java	(.../UserOrgSaveController.java)	(revision 063b75b0ad3ad6365af21a3f77a82700f1bfdc5f)
+++ lams_admin/src/java/org/lamsfoundation/lams/admin/web/controller/UserOrgSaveController.java	(.../UserOrgSaveController.java)	(revision 064661349150076f41ef249b55b054a72f6a3fb5)
@@ -26,7 +26,6 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
@@ -36,6 +35,7 @@
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import org.apache.commons.lang.StringUtils;
 import org.apache.log4j.Logger;
 import org.lamsfoundation.lams.admin.web.form.UserOrgForm;
 import org.lamsfoundation.lams.usermanagement.Organisation;
@@ -113,8 +113,9 @@
 	Organisation organisation = (Organisation) userManagementService.findById(Organisation.class, orgId);
 	Set uos = organisation.getUserOrganisations();
 
-	String[] userIds = userOrgForm.getUserIds();
-	List<String> userIdList = userIds == null ? Collections.emptyList() : Arrays.asList(userIds);
+	String[] userIds = StringUtils.isBlank(userOrgForm.getUserIds()) ? null : userOrgForm.getUserIds().split(",");
+	List<Integer> userIdList = Arrays.stream(userIds).filter(StringUtils::isNotBlank)
+		.collect(Collectors.mapping(userId -> Integer.valueOf(userId), Collectors.toList()));
 	log.debug("new user membership of orgId=" + orgId + " will be: " + userIdList);
 	Set<Integer> removedUserIds = new TreeSet<>();
 
@@ -123,7 +124,7 @@
 	while (iter.hasNext()) {
 	    UserOrganisation uo = (UserOrganisation) iter.next();
 	    Integer userId = uo.getUser().getUserId();
-	    if (userIdList.indexOf(userId.toString()) < 0) {
+	    if (!userIdList.contains(userId)) {
 		User user = (User) userManagementService.findById(User.class, userId);
 		Set userUos = user.getUserOrganisations();
 		userUos.remove(uo);
@@ -138,8 +139,7 @@
 	}
 	// add UserOrganisations that are in form data
 	List<UserOrganisation> newUserOrganisations = new ArrayList<>();
-	for (int i = 0; i < userIdList.size(); i++) {
-	    Integer userId = new Integer(userIdList.get(i));
+	for (Integer userId : userIdList) {
 	    Iterator iter2 = uos.iterator();
 	    boolean alreadyInOrg = false;
 	    while (iter2.hasNext()) {
@@ -205,8 +205,8 @@
 	StringBuilder userNames = new StringBuilder();
 	for (Integer userId : userIds) {
 	    User user = userManagementService.getUserById(userId);
-	    userNames.append(user.getFirstName()).append(" ").append(user.getLastName())
-		    .append(" (").append(user.getLogin()).append("), ");
+	    userNames.append(user.getFirstName()).append(" ").append(user.getLastName()).append(" (")
+		    .append(user.getLogin()).append("), ");
 	}
 	return userNames.delete(userNames.length() - 2, userNames.length()).toString();
     }
Index: lams_admin/src/java/org/lamsfoundation/lams/admin/web/form/UserOrgForm.java
===================================================================
diff -u -r550e1b37b507779064955267ef47e9085f791357 -r064661349150076f41ef249b55b054a72f6a3fb5
--- lams_admin/src/java/org/lamsfoundation/lams/admin/web/form/UserOrgForm.java	(.../UserOrgForm.java)	(revision 550e1b37b507779064955267ef47e9085f791357)
+++ lams_admin/src/java/org/lamsfoundation/lams/admin/web/form/UserOrgForm.java	(.../UserOrgForm.java)	(revision 064661349150076f41ef249b55b054a72f6a3fb5)
@@ -28,7 +28,7 @@
 
     private String orgName;
 
-    private String[] userIds;
+    private String userIds;
 
     public Integer getOrgId() {
 	return orgId;
@@ -46,12 +46,11 @@
 	this.orgName = orgName;
     }
 
-    public String[] getUserIds() {
+    public String getUserIds() {
 	return userIds;
     }
 
-    public void setUserIds(String[] userIds) {
+    public void setUserIds(String userIds) {
 	this.userIds = userIds;
     }
-
-}
+}
\ No newline at end of file
Index: lams_admin/web/userorg.jsp
===================================================================
diff -u -r92b07870b09c49b9db34996fab8e99651d2d2538 -r064661349150076f41ef249b55b054a72f6a3fb5
--- lams_admin/web/userorg.jsp	(.../userorg.jsp)	(revision 92b07870b09c49b9db34996fab8e99651d2d2538)
+++ lams_admin/web/userorg.jsp	(.../userorg.jsp)	(revision 064661349150076f41ef249b55b054a72f6a3fb5)
@@ -141,9 +141,11 @@
 		}
 		
 		function populateForm() {
+			let userIds = '';
 			jQuery("li", "div#existing").each(function() {
-				jQuery("form", "div#form").append("<input type='checkbox' name='userIds' value='"+jQuery(this).attr("id")+"' checked='checked' style='display:none;'>");
+				userIds += $(this).attr("id") + ',';
 			});
+			$('#userOrgForm #userIds').val(userIds);
 			return true;
 		}
 	</script>
@@ -210,6 +212,7 @@
 					<form:form action="./userorgsave.do" modelAttribute="userOrgForm" id="userOrgForm" method="post">
 						<input type="hidden" name="<csrf:tokenname/>" value="<csrf:tokenvalue/>"/>
 						<form:hidden path="orgId" />
+						<form:hidden path="userIds" />
 						<a href="<lams:LAMSURL/>admin/orgmanage.do?org=1" class="btn btn-default"><fmt:message key="admin.cancel"/></a>
 						<input type="submit" id="nextButton" class="btn btn-primary loffset5" onclick="return populateForm();" value="<fmt:message key="label.next"/>" />
 					</form:form>