diff --git a/components/team/EditTeamModal.tsx b/components/team/EditTeamModal.tsx
index b03fdb99..347a7ba6 100644
--- a/components/team/EditTeamModal.tsx
+++ b/components/team/EditTeamModal.tsx
@@ -62,7 +62,8 @@ export default function EditTeamModal(props) {
                     <td className="text-right py-2 px-1">
                       {member.email !== session.user.email &&
                       <button
-                        onClick={() => removeMember(member)}
+                        type="button"
+                        onClick={(e) => removeMember(member)}
                         className="btn-sm text-xs bg-transparent px-3 py-1 rounded ml-2">
                         <UserRemoveIcon className="text-red-400 group-hover:text-gray-500 flex-shrink-0 -mt-1 mr-1 h-4 w-4 inline"/>
                       </button>
@@ -76,20 +77,20 @@ export default function EditTeamModal(props) {
             <div className="mb-4 border border-red-400 rounded p-2 px-4">
               <p className="block text-sm font-medium text-gray-700">Tick the box to disband this team.</p>
               <label className="mt-1">
-                <input type="checkbox" name="title" id="title" onChange={(e) => setCheckedDisbandTeam(e.target.checked)} required className="shadow-sm mr-2 focus:ring-blue-500 focus:border-blue-500  sm:text-sm border-gray-300 rounded-md" />
+                <input type="checkbox" onChange={(e) => setCheckedDisbandTeam(e.target.checked)} className="shadow-sm mr-2 focus:ring-blue-500 focus:border-blue-500  sm:text-sm border-gray-300 rounded-md" />
                 Disband this team
               </label>
             </div>
           </div>
           <div className="mt-5 sm:mt-4 sm:flex sm:flex-row-reverse">
-            {!checkedDisbandTeam && <button type="submit" className="btn btn-primary">
+            {/*!checkedDisbandTeam && <button type="submit" className="btn btn-primary">
               Update
-            </button>}
+            </button>*/}
             {checkedDisbandTeam && <button onClick={deleteTeam} className="btn bg-red-700 rounded text-white px-2 font-medium text-sm">
               Disband Team
             </button>}
             <button onClick={props.onExit} type="button" className="btn btn-white mr-2">
-              Cancel
+              Close
             </button>
           </div>
         </form>
diff --git a/components/team/MemberInvitationModal.tsx b/components/team/MemberInvitationModal.tsx
index e4472b09..36e0d564 100644
--- a/components/team/MemberInvitationModal.tsx
+++ b/components/team/MemberInvitationModal.tsx
@@ -1,8 +1,22 @@
-import {useEffect, useState} from "react";
-import {UsersIcon} from "@heroicons/react/outline";
+import { UsersIcon } from "@heroicons/react/outline";
+import { useState } from "react";
 
 export default function MemberInvitationModal(props) {
 
+  const [ errorMessage, setErrorMessage ] = useState('');
+
+  const handleError = async (res) => {
+
+    const responseData = await res.json();
+
+    if (res.ok === false) {
+      setErrorMessage(responseData.message);
+      throw new Error(responseData.message);
+    }
+
+    return responseData;
+  };
+
   const inviteMember = (e) => {
 
     e.preventDefault();
@@ -19,7 +33,9 @@ export default function MemberInvitationModal(props) {
       headers: {
         'Content-Type': 'application/json'
       }
-    }).then(props.onExit);
+    }).then(handleError).then(props.onExit).catch( (e) => {
+      // do nothing.
+    });
   };
 
   return (<div className="fixed z-10 inset-0 overflow-y-auto" aria-labelledby="modal-title" role="dialog" aria-modal="true">
@@ -60,6 +76,7 @@ export default function MemberInvitationModal(props) {
               </label>
             </div>
           </div>
+          {errorMessage && <p className="text-red-700 text-sm"><span class="font-bold">Error: </span>{errorMessage}</p>}
           <div className="mt-5 sm:mt-4 sm:flex sm:flex-row-reverse">
             <button type="submit" className="btn btn-primary">
               Invite
diff --git a/pages/api/teams.ts b/pages/api/teams.ts
index abd96c3d..33d1038d 100644
--- a/pages/api/teams.ts
+++ b/pages/api/teams.ts
@@ -1,7 +1,6 @@
 import type { NextApiRequest, NextApiResponse } from 'next';
 import prisma from '../../lib/prisma';
 import {getSession} from "next-auth/client";
-import {create} from "domain";
 
 export default async function handler(req: NextApiRequest, res: NextApiResponse) {
 
@@ -13,6 +12,9 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
   }
 
   if (req.method === "POST") {
+
+    // TODO: Prevent creating a team with identical names?
+
     const createTeam = await prisma.team.create({
       data: {
         name: req.body.name,
diff --git a/pages/api/teams/[team]/invite.ts b/pages/api/teams/[team]/invite.ts
index d8170401..1a8f2415 100644
--- a/pages/api/teams/[team]/invite.ts
+++ b/pages/api/teams/[team]/invite.ts
@@ -21,7 +21,7 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
   });
 
   if (!team) {
-    return res.status(404).json({message: "Unable to find team to invite user to."});
+    return res.status(404).json({message: "Invalid team"});
   }
 
   const invitee = await prisma.user.findFirst({
@@ -34,17 +34,29 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
   });
 
   if (!invitee) {
-    return res.status(404).json({message: "Missing user, currently unsupported."});
+    return res.status(400).json({
+      message: `Invite failed because there is no corresponding user for ${req.body.usernameOrEmail}`});
   }
 
   // create provisional membership
-  const createMembership = await prisma.membership.create({
-    data: {
-      teamId: parseInt(req.query.team),
-      userId: invitee.id,
-      role: req.body.role,
-    },
-  });
+  try {
+    const createMembership = await prisma.membership.create({
+      data: {
+        teamId: parseInt(req.query.team),
+        userId: invitee.id,
+        role: req.body.role,
+      },
+    });
+  }
+  catch (err) {
+    if (err.code === "P2002") { // unique constraint violation
+      return res.status(409).json({
+        message: 'This user is a member of this team / has a pending invitation.',
+      });
+    } else {
+      throw err; // rethrow
+    }
+  };
 
   // inform user of membership by email
   if (req.body.sendEmailInvitation) {