diff --git a/lib/Exceptions/ConflictException.php b/lib/Exceptions/ConflictException.php
index b44bff031..53c33601c 100644
--- a/lib/Exceptions/ConflictException.php
+++ b/lib/Exceptions/ConflictException.php
@@ -21,16 +21,24 @@
  *
  */
 
-namespace OCA\Deck;
+namespace OCA\Deck\Exceptions;
 
+use OCA\Deck\StatusException;
 
-class ConflictException extends \Exception {
+class ConflictException extends StatusException {
 
-	public function __construct($message) {
+	private $data;
+
+	public function __construct($message, $data = null) {
 		parent::__construct($message);
+		$this->data = $data;
 	}
 
 	public function getStatus() {
 		return 409;
 	}
+
+	public function getData() {
+		return $this->data;
+	}
 }
\ No newline at end of file
diff --git a/lib/Middleware/ExceptionMiddleware.php b/lib/Middleware/ExceptionMiddleware.php
index a4f0610ee..416ef105a 100644
--- a/lib/Middleware/ExceptionMiddleware.php
+++ b/lib/Middleware/ExceptionMiddleware.php
@@ -25,6 +25,7 @@ namespace OCA\Deck\Middleware;
 
 use OCA\Deck\Controller\PageController;
 use OCA\Deck\StatusException;
+use OCA\Deck\Exceptions\ConflictException;
 use OCP\AppFramework\Db\DoesNotExistException;
 use OCP\AppFramework\Middleware;
 use OCP\AppFramework\Http\JSONResponse;
@@ -63,6 +64,17 @@ class ExceptionMiddleware extends Middleware {
 	 * @throws \Exception
 	 */
 	public function afterException($controller, $methodName, \Exception $exception) {
+		if ($exception instanceof ConflictException) {
+			if ($this->config->getSystemValue('loglevel', Util::WARN) === Util::DEBUG) {
+				$this->logger->logException($exception);
+			}
+			return new JSONResponse([
+				'status' => $exception->getStatus(),
+				'message' => $exception->getMessage(),
+				'data' => $exception->getData(),
+			], $exception->getStatus());
+		}
+		
 		if ($exception instanceof StatusException) {
 			if ($this->config->getSystemValue('loglevel', Util::WARN) === Util::DEBUG) {
 				$this->logger->logException($exception);
diff --git a/lib/Service/FileService.php b/lib/Service/FileService.php
index 02f3ab6bc..0aafd45ce 100644
--- a/lib/Service/FileService.php
+++ b/lib/Service/FileService.php
@@ -26,6 +26,7 @@ namespace OCA\Deck\Service;
 use OC\Security\CSP\ContentSecurityPolicyManager;
 use OCA\Deck\Db\Attachment;
 use OCA\Deck\StatusException;
+use OCA\Deck\Exceptions\ConflictException;
 use OCP\AppFramework\Http\ContentSecurityPolicy;
 use OCP\AppFramework\Http\EmptyContentSecurityPolicy;
 use OCP\AppFramework\Http\FileDisplayResponse;
@@ -42,7 +43,7 @@ use OCP\IConfig;
 use OCP\IL10N;
 use OCP\ILogger;
 use OCP\IRequest;
-use OCP\Deck\ConflictException;
+
 
 class FileService implements IAttachmentService {
 
@@ -154,7 +155,7 @@ class FileService implements IAttachmentService {
 		$folder = $this->getFolder($attachment);
 		$fileName = $file['name'];
 		if ($folder->fileExists($fileName)) {
-			throw new ConflictException('File already exists.');
+			throw new ConflictException('File already exists.', $attachment);
 		}
 
 		$target = $folder->newFile($fileName);
diff --git a/src/components/card/CardSidebarTabAttachments.vue b/src/components/card/CardSidebarTabAttachments.vue
index 8f53a2d56..de401f96d 100644
--- a/src/components/card/CardSidebarTabAttachments.vue
+++ b/src/components/card/CardSidebarTabAttachments.vue
@@ -45,17 +45,38 @@
 			type="file"
 			style="display: none;"
 			@change="onLocalAttachmentSelected">
+
+		<Modal v-if="modalShow" title="File already exists" @close="modalShow=false">
+			<div class="modal__content">
+				<h2>{{ t('deck', 'File already exists') }}</h2>
+				<p>
+					{{ t('deck', 'A file with the name') }}
+					{{ file.name }}
+					{{ t('deck', 'already exists.') }}
+				</p>
+				<p>
+					{{ t('deck', 'Do you want to overwrite it?') }}
+				</p>
+				<button class="primary" @click="overrideAttachment">
+					{{ t('deck', 'Yes') }}
+				</button>
+				<button @click="modalShow=false">
+					{{ t('deck', 'No') }}
+				</button>
+			</div>
+		</Modal>
 	</div>
 </template>
 
 <script>
-import { Actions, ActionButton } from '@nextcloud/vue'
+import { Actions, ActionButton, Modal } from '@nextcloud/vue'
 
 export default {
 	name: 'CardSidebarTabAttachments',
 	components: {
 		Actions,
 		ActionButton,
+		Modal,
 	},
 	props: {
 		card: {
@@ -65,6 +86,9 @@ export default {
 	},
 	data() {
 		return {
+			modalShow: false,
+			file: '',
+			overrideError: null
 		}
 	},
 	computed: {
@@ -85,11 +109,12 @@ export default {
 			bodyFormData.append('cardId', this.card.id)
 			bodyFormData.append('type', 'deck_file')
 			bodyFormData.append('file', e.target.files[0])
+			this.file = e.target.files[0]
 			try {
-				await this.$store.dispatch('createAttachment', { cardId: this.card.id, formData: bodyFormData })
+				const data = await this.$store.dispatch('createAttachment', { cardId: this.card.id, formData: bodyFormData })
+				console.log(data)
 			} catch (e) {
-				console.log("doppelt")
-				console.log(e)
+				this.modalShow = true
 			}
 		},
 		deleteAttachment(attachment) {
@@ -105,6 +130,15 @@ export default {
 		attachmentUrl(attachment) {
 			return OC.generateUrl(`/apps/deck/cards/${attachment.cardId}/attachment/${attachment.id}`)
 		},
+		overrideAttachment() {
+			const bodyFormData = new FormData()
+			bodyFormData.append('cardId', this.card.id)
+			bodyFormData.append('type', 'deck_file')
+			bodyFormData.append('file', this.file)
+			this.$store.dispatch('updateAttachment', { cardId: this.card.id, attachmentId: 1, formData: bodyFormData })
+
+			this.modalShow = false
+		},
 	},
 }
 </script>
@@ -117,4 +151,16 @@ export default {
 		height: 32px;
 		background-size: contain;
 	}
+	.modal__content {
+		width: 25vw;
+		min-width: 250px;
+		height: 120px;
+		text-align: center;
+		margin: 20px 20px 60px 20px;
+	}
+
+	.modal__content button {
+		float: right;
+		margin: 40px 3px 3px 0;
+	}
 </style>
diff --git a/src/services/AttachmentApi.js b/src/services/AttachmentApi.js
index 751ccdca4..66cab0934 100644
--- a/src/services/AttachmentApi.js
+++ b/src/services/AttachmentApi.js
@@ -38,7 +38,7 @@ export class AttachmentApi {
 	}
 
 	async createAttachment({ cardId, formData }) {
-		const response = await axios({
+		 const response = await axios({
 			method: 'POST',
 			url: this.url(`/cards/${cardId}/attachment`),
 			data: formData,
@@ -46,6 +46,15 @@ export class AttachmentApi {
 		return response.data
 	}
 
+	async updateAttachment({ cardId, attachmentId, formData }) {
+		const response = await axios({
+		   method: 'PUT',
+		   url: this.url(`/cards/${cardId}/attachment/${attachmentId}`),
+		   data: formData,
+	   })
+	   return response.data
+	}
+
 	async deleteAttachment(attachment) {
 		await axios({
 			method: 'DELETE',
diff --git a/src/store/attachment.js b/src/store/attachment.js
index ffa3c21d2..f8651f42a 100644
--- a/src/store/attachment.js
+++ b/src/store/attachment.js
@@ -47,6 +47,10 @@ export default {
 			}
 		},
 
+		updateAttachment(state, { cardId, attachment }) {
+			Vue.set(state.attachments, cardId, attachment)
+		},
+
 		deleteAttachment(state, deletedAttachment) {
 			const existingIndex = state.attachments[deletedAttachment.cardId].findIndex(a => a.id === deletedAttachment.id)
 			if (existingIndex !== -1) {
@@ -67,6 +71,11 @@ export default {
 			commit('cardIncreaseAttachmentCount', cardId)
 		},
 
+		async updateAttachment({ commit }, { cardId, attachmentId, formData }) {
+			const attachment = await apiClient.updateAttachment({ cardId, attachmentId, formData })
+			commit('updateAttachment', { cardId, attachment })
+		},
+
 		async deleteAttachment({ commit }, attachment) {
 			await apiClient.deleteAttachment(attachment)
 			commit('deleteAttachment', attachment)