diff --git a/webapp/src/api/games.js b/webapp/src/api/games.js
index 6f3cb01..1cb0d3b 100644
--- a/webapp/src/api/games.js
+++ b/webapp/src/api/games.js
@@ -73,11 +73,12 @@ export default function useGamesApi() {
 
     const pushGameMove = ({ uuid, move, message }) => {
         doPushing(`/api/game/${uuid}/move`, 'PUT', { move, message }, {
-            onPushing: (isPushing) => dispatchGuide({ type: 'UUIDpushing', uuid, what: isPushing && {moveFrom: move[0], moveTo: move[1]} }),
+            onPushing: (isPushing) => dispatchGuide({ type: 'UUIDpushing', uuid, what: isPushing && { moveFrom: move[0], moveTo: move[1] } }),
+            onBadReq: (message) => dispatchGuide({ type: 'UUIDerror', uuid, error: { message, moveFrom: move[0], moveTo: move[1] } }),
             onSuccess: (game) => {
                 dispatchState({ type: 'update', game });
-                dispatchGuide({ type: 'UUIDmessage', uuid, message: ''});
-            }
+                dispatchGuide({ type: 'UUIDmessage', uuid, message: '' });
+            },
         })
     }
 
diff --git a/webapp/src/container/Games.css b/webapp/src/container/Games.css
index 5b5dca7..27ce429 100644
--- a/webapp/src/container/Games.css
+++ b/webapp/src/container/Games.css
@@ -97,10 +97,25 @@
 
 .GameBoard {
     padding-left: 30px;
+    width: 275px;
 }
 
 .Message2Opponent {
     margin: 10px;
     margin-left: 30px;
-    width: 270px;
+    width: 275px;
+}
+
+.BadMove {
+    position: fixed;
+    width: 275px;
+    top: 250px;
+    cursor: default; /* disable 'I beam' cursor change */
+    text-align: center;
+    border-radius: 3px;
+    background-color: rgba(255, 80, 80, 0.3);
+}
+
+.BadMove:hover {
+    background-color: rgba(255, 80, 80, 0.7);
 }
\ No newline at end of file
diff --git a/webapp/src/container/Games.jsx b/webapp/src/container/Games.jsx
index 7a3e880..44d5f4f 100644
--- a/webapp/src/container/Games.jsx
+++ b/webapp/src/container/Games.jsx
@@ -34,7 +34,6 @@ export default function Games({ games, players }) {
             <ActionPanel gamesApi={games.api} />
             <GameBoardRoutes dispatchGuide={gamesDispatchGuide} gamesApi={games.api} username={players.user.name} />
             <Message2OpponentRoutes dispatchGuide={gamesDispatchGuide} />
-            {/* <GameMessage /> */}
           </div>
 
         </div >
@@ -156,10 +155,11 @@ function GameBoardRoutes({ dispatchGuide, gamesApi, username }) {
   const games = useContext(GamesStateContext);
   const guide = useContext(GamesGuideContext);
 
-  const fromUUID = (uuid) => (!uuid) ? [{}, null] :
+  const fromUUID = (uuid) => (!uuid) ? [{}, null, null] :
     [
       games.find((game) => game.uuid === uuid) || {}, // game
-      guide.UUIDpushing[uuid]                         // pushing
+      guide.UUIDpushing[uuid],                        // pushing
+      guide.UUIDerror[uuid]                           // error (aka bad move)
     ];
 
   const onStoneClick = (uuid, cellId) => {
@@ -191,6 +191,7 @@ function GameBoardRoutes({ dispatchGuide, gamesApi, username }) {
           username={username}
           getGame={() => fromUUID(guide.selectedUUID.active)}
           onStoneMove={(uuid, move) => gamesApi.pushGameMove({ uuid, move, message: guide.UUIDmessage[uuid] })}
+          dispatchGuide={dispatchGuide}
         />
       } />
 
diff --git a/webapp/src/container/games/BadMove.jsx b/webapp/src/container/games/BadMove.jsx
new file mode 100644
index 0000000..16dac2d
--- /dev/null
+++ b/webapp/src/container/games/BadMove.jsx
@@ -0,0 +1,14 @@
+import React from 'react';
+
+export default function BadMove({ dispatchGuide, uuid, message }) {
+  if (!dispatchGuide || !uuid || !message)
+    return;
+
+  return (
+    <div className='BadMove'
+      onClick={() => dispatchGuide({ type: 'UUIDerror', uuid, error: {} })}
+    >
+      {message}
+    </div>
+  )
+}
\ No newline at end of file
diff --git a/webapp/src/container/games/GameBoard.jsx b/webapp/src/container/games/GameBoard.jsx
index 437048e..afd8303 100644
--- a/webapp/src/container/games/GameBoard.jsx
+++ b/webapp/src/container/games/GameBoard.jsx
@@ -1,10 +1,10 @@
 import React from 'react';
-
 import { Color, Player, Board } from '../../components/Checkers';
 import './GameBoard.css';
+import BadMove from './BadMove';
 
-export default function GameBoard({ username, getGame, onStoneClick, onStoneMove }) {
-  const [game, isPushing] = getGame();
+export default function GameBoard({ dispatchGuide, username, getGame, onStoneClick, onStoneMove }) {
+  const [game, isPushing, error] = getGame();
 
   const myName = game.opponentName ? username : '';
   const opponentColor = Color.opposite(game.myColor);
@@ -14,11 +14,17 @@ export default function GameBoard({ username, getGame, onStoneClick, onStoneMove
     (cellId) => onStoneClick(game.uuid, cellId);
 
   const optionalOnStoneMove = (typeof onStoneMove !== 'function' || isPushing) ? null :
-    (move) =>  {
+    (move) => {
       if (move[0] !== move[1] && game.board[move[1]] === undefined)
         onStoneMove(game.uuid, move)
     };
 
+  const currMove = (() => {
+    if (isPushing) return [isPushing.moveFrom, isPushing.moveTo];
+    if (error?.moveFrom && error?.moveTo) return [error.moveFrom, error.moveTo];
+    return [];
+  })(); // <<-- execute
+
   return (
     <div className='GameBoard'>
       <Player
@@ -29,7 +35,7 @@ export default function GameBoard({ username, getGame, onStoneClick, onStoneMove
         board={game.board}
         flip={flipBoard}
         prevMove={game.previousMove}
-        currMove={[isPushing?.moveFrom, isPushing?.moveTo]}
+        currMove={currMove}
         onStoneClick={optionalOnStoneClick}
         onStoneMove={optionalOnStoneMove}
       />
@@ -37,6 +43,7 @@ export default function GameBoard({ username, getGame, onStoneClick, onStoneMove
         color={game.myColor || Color.white}
         name={myName}
       />
+      <BadMove dispatchGuide={dispatchGuide} uuid={game?.uuid} message={error?.message} />
     </div>
   )
 }
\ No newline at end of file
diff --git a/webapp/src/hook/api.js b/webapp/src/hook/api.js
index 2e5b71b..2fc88a3 100644
--- a/webapp/src/hook/api.js
+++ b/webapp/src/hook/api.js
@@ -21,7 +21,7 @@ export function usePolling(uri, { onSuccess, onPolling }, mode = null) {
         setPolling(true);
         if (onPolling)
             onPolling(true);
-        
+
         initialPollRef.current = false;
 
         fetch(uri)
@@ -62,7 +62,7 @@ export function usePolling(uri, { onSuccess, onPolling }, mode = null) {
     }, [initialPoll, mode, intervalTimerId, isPolling, pollData, stopPollInterval]);
 }
 
-export async function doPushing(uri, method, data, { onSuccess, onPushing }) {
+export async function doPushing(uri, method, data, { onSuccess, onBadReq, onPushing }) {
     if (onPushing)
         onPushing(true);
 
@@ -75,14 +75,22 @@ export async function doPushing(uri, method, data, { onSuccess, onPushing }) {
             body: JSON.stringify(data), // body data type must match "Content-Type" header
         });
 
+        if (response.status === 400 && onBadReq) {
+            const content = (response.headers.get('Content-Type') === "application/json")
+                ? await response.json()
+                : {};
+
+            return onBadReq(content.message);
+        }
+
         if (!response.ok) {
             return console.warn(`Unexpected response status: ${response.status}`, response);
         }
 
         if (onSuccess) {
-            var content = (response.headers.get('Content-Type') === "application/json")
+            const content = (response.headers.get('Content-Type') === "application/json")
                 ? await response.json()
-                : null;
+                : {};
 
             onSuccess(content);
         }
diff --git a/webapp/src/reducer/games.js b/webapp/src/reducer/games.js
index 14aa963..a7092d0 100644
--- a/webapp/src/reducer/games.js
+++ b/webapp/src/reducer/games.js
@@ -76,6 +76,9 @@ export const gamesGuideTemplate = {
   UUIDpushing: { // UUIDpushing[uuid]
   },
 
+  UUIDerror: { // UUIDerror[uuid]
+  },
+
   isPolling: false,
 };
 
@@ -116,6 +119,12 @@ function gamesGuideReducer(state, action) {
       return next;
     }
 
+    case 'UUIDerror': {
+      const next = { ...state };
+      next.UUIDerror[action.uuid] = action.error;
+      return next;
+    }
+
     default:
       throw Error('GamesGuide: unknown action.type: ' + action.type);
   }