diff --git a/src/client/assets/js/index.js b/src/client/assets/js/index.js
index 5922650..8e07644 100644
--- a/src/client/assets/js/index.js
+++ b/src/client/assets/js/index.js
@@ -12,6 +12,8 @@ const outputMinMem = document.querySelector('#outputMinMem')
 const outputMaxMem = document.querySelector('#outputMaxMem')
 const totalMem = os.totalmem() / (1.049 * Math.pow(10, 6))
 const sidebar = document.querySelector("#sidebar-content")
+const invalidateButton = document.querySelector("#invalidateData")
+let gameLaunching = false
 
 let selectedChapter = -1;
 
@@ -43,6 +45,7 @@ launchBtn.addEventListener("click", e => {
         launchBtn.disabled = true
         localStorage.setItem("minMem", minMem.value)
         localStorage.setItem("maxMem", maxMem.value)
+        gameLaunching = true
     } else{
         ipcRenderer.send('notification', {
             title: "Erreur de lancement",
@@ -57,7 +60,8 @@ document.querySelector("#web").addEventListener("click", e => {
 })
 
 document.querySelector("#options").addEventListener("click", e => {
-    fullscreen.style.display = "block"
+    if(!gameLaunching)
+        fullscreen.style.display = "block"
 })
 
 document.querySelector("#discord").addEventListener("click", e => {
@@ -68,6 +72,17 @@ document.querySelector("#close").addEventListener("click", e => {
     fullscreen.style.display = "none"
 });
 
+invalidateButton.addEventListener("click", e => {
+    invalidateButton.disabled = true
+    invalidateButton.childNodes[0].nodeValue = "Opération en cours"
+    ipcRenderer.send('invalidateData')
+})
+
+ipcRenderer.on("invalidated", e => {
+    invalidateButton.disabled = false
+    invalidateButton.childNodes[0].nodeValue = "Supprimer et retélécharger les bibliothèques"
+})
+
 ipcRenderer.on("progress", (e, args) => {
     progressBar.style.width = (args.task / Math.max(args.total, args.task)) * 100 + "%"
     loadingMessage.innerHTML = "Téléchargement de " + args.type + ": " + args.task + " sur " + Math.max(args.total, args.task)
@@ -80,6 +95,7 @@ ipcRenderer.on("close", (e, args) => {
     loadingMessage.innerHTML = "Chargement de Minecraft en cours..."
     progressBar.style.width = "0"
     launchBtn.disabled = false
+    gameLaunching = false
 })
 
 ipcRenderer.on('launch', (e, args) => {
diff --git a/src/client/assets/js/login.js b/src/client/assets/js/login.js
index 3214a52..e62d4bc 100644
--- a/src/client/assets/js/login.js
+++ b/src/client/assets/js/login.js
@@ -1,9 +1,12 @@
-user = document.querySelector('#nickname')
-password = document.querySelector('#password')
+const form = document.querySelector('#login-form')
+const user = document.querySelector('#nickname')
+const password = document.querySelector('#password')
 
-document.querySelector('#login-form').addEventListener("submit", (e) => {
+
+form.addEventListener("submit", (e) => {
     e.preventDefault()
-    if(user.value){
+    form.disabled = true
+    if(user.value) {
         ipcRenderer.send("login", {
             user: user.value,
             pass: password.value
@@ -16,3 +19,7 @@ document.querySelector('#login-form').addEventListener("submit", (e) => {
     }
     
 })
+
+ipcRenderer.on("loginError", event => {
+    form.disabled = false
+})
\ No newline at end of file
diff --git a/src/client/index.html b/src/client/index.html
index edd206d..5abed92 100644
--- a/src/client/index.html
+++ b/src/client/index.html
@@ -28,6 +28,8 @@
                 <input type="range" min="1024" max="2048" step="128" value="1" class="slider" id="minMem"><br />
                 <label for="maxMem">mémoire maximale : <span id="outputMaxMem"></span></label><br />
                 <input type="range" min="1024" max="2048" step="128" value="1" class="slider" id="maxMem"><br />
+                <h4>Au secours, mon jeu ne démarre pas</h4>
+                <button id="invalidateData">Supprimer et retélécharger les bibliothèques</button>
         </div>
     </div>
     <div id="content">
diff --git a/src/server/main.js b/src/server/main.js
index a034d6b..24749f5 100644
--- a/src/server/main.js
+++ b/src/server/main.js
@@ -64,6 +64,10 @@ ipcMain.on("login", (event, args) => {
     minecraft.login(event, win, showNotification, args.user, args.pass)
 })
 
+ipcMain.on("invalidateData", event => {
+    minecraft.invalidateData(event)
+})
+
 ipcMain.on("launch", (event, args) => {
   minecraft.launch(event, showNotification, args)
 })
diff --git a/src/server/minecraft.js b/src/server/minecraft.js
index 7261fe7..dbe2559 100644
--- a/src/server/minecraft.js
+++ b/src/server/minecraft.js
@@ -25,6 +25,7 @@ class Minecraft {
                     event.sender.send("nick", { name: v.name })
                 })
             }).catch((err) => {
+                event.sender.send("loginError")
                 logger.error(err)
                 showNotification("Erreur de connexion")
             })
@@ -51,7 +52,7 @@ class Minecraft {
                     }
                 })
                 this.launcher.on('debug', (e) => logger.info(`debug: ${e}`));
-                // this.launcher.on('data', (e) => logger.info(`data: ${e}`));
+                this.launcher.on('data', (e) => logger.info(`data: ${e}`));
                 this.launcher.on('progress', (e) => {
                     event.sender.send("progress", e)
                     logger.info(`progress ${e.type} :${e.task} / ${e.total}`)
@@ -261,6 +262,19 @@ class Minecraft {
             })
         })
     }
+
+    invalidateData(event) {
+        const assets = join(this.minecraftpath, 'assets')
+        const librairies = join(this.minecraftpath,'libraries')
+        const natives = join(this.minecraftpath, 'natives')
+        if(fs.existsSync(assets))
+            fs.rmdirSync(assets, { recursive: true })
+        if(fs.existsSync(librairies))
+            fs.rmdirSync(librairies, { recursive: true })
+        if(fs.existsSync(natives))
+            fs.rmdirSync(natives, { recursive: true })
+        event.sender.send("invalidated")
+    }
 }
 
 module.exports = new Minecraft
\ No newline at end of file