diff --git a/api/src/channel/lib/__test__/subscriber.mock.ts b/api/src/channel/lib/__test__/subscriber.mock.ts
index 5f2bda7e..ea144104 100644
--- a/api/src/channel/lib/__test__/subscriber.mock.ts
+++ b/api/src/channel/lib/__test__/subscriber.mock.ts
@@ -28,6 +28,8 @@ export const subscriberInstance: Subscriber = {
     name: 'web-channel',
   },
   labels: [],
+  avatar: null,
+  context: {},
   ...modelInstance,
 };
 
diff --git a/api/src/chat/schemas/subscriber.schema.ts b/api/src/chat/schemas/subscriber.schema.ts
index f2a8e1cf..ba3ea80a 100644
--- a/api/src/chat/schemas/subscriber.schema.ts
+++ b/api/src/chat/schemas/subscriber.schema.ts
@@ -80,13 +80,13 @@ export class SubscriberStub extends BaseSchema {
     ref: 'User',
     default: null,
   })
-  assignedTo?: unknown;
+  assignedTo: unknown;
 
   @Prop({
     type: Date,
     default: null,
   })
-  assignedAt?: Date | null;
+  assignedAt: Date | null;
 
   @Prop({
     type: Date,
@@ -110,13 +110,13 @@ export class SubscriberStub extends BaseSchema {
     ref: 'Attachment',
     default: null,
   })
-  avatar?: unknown;
+  avatar: unknown;
 
   @Prop({
     type: Object,
     default: { vars: {} },
   })
-  context?: SubscriberContext;
+  context: SubscriberContext;
 
   static getChannelData<
     C extends ChannelName,
@@ -131,11 +131,11 @@ export class Subscriber extends SubscriberStub {
   @Transform(({ obj }) => obj.labels.map((label) => label.toString()))
   labels: string[];
 
-  @Transform(({ obj }) => (obj.assignedTo ? obj.assignedTo.toString() : null))
-  assignedTo?: string | null;
+  @Transform(({ obj }) => obj.assignedTo?.toString() || null)
+  assignedTo: string | null;
 
   @Transform(({ obj }) => obj.avatar?.toString() || null)
-  avatar?: string | null;
+  avatar: string | null;
 }
 
 @Schema({ timestamps: true })
@@ -144,7 +144,7 @@ export class SubscriberFull extends SubscriberStub {
   labels: Label[];
 
   @Type(() => User)
-  assignedTo?: User | null;
+  assignedTo: User | null;
 
   @Type(() => Attachment)
   avatar: Attachment | null;
diff --git a/api/src/chat/services/bot.service.spec.ts b/api/src/chat/services/bot.service.spec.ts
index dcebfa35..c4bf517a 100644
--- a/api/src/chat/services/bot.service.spec.ts
+++ b/api/src/chat/services/bot.service.spec.ts
@@ -193,11 +193,11 @@ describe('BlockService', () => {
     });
 
     const [block] = await blockService.findAndPopulate({ patterns: ['Hi'] });
-    const webSubscriber = await subscriberService.findOne({
+    const webSubscriber = (await subscriberService.findOne({
       foreign_id: 'foreign-id-web-1',
-    });
+    }))!;
 
-    event.setSender(webSubscriber!);
+    event.setSender(webSubscriber);
 
     let hasBotSpoken = false;
     const clearMock = jest
@@ -210,15 +210,15 @@ describe('BlockService', () => {
           isFallback: boolean,
         ) => {
           expect(actualConversation).toEqualPayload({
-            sender: webSubscriber!.id,
+            sender: webSubscriber.id,
             active: true,
             next: [],
             context: {
               user: {
-                first_name: webSubscriber!.first_name,
-                last_name: webSubscriber!.last_name,
+                first_name: webSubscriber.first_name,
+                last_name: webSubscriber.last_name,
                 language: 'en',
-                id: webSubscriber!.id,
+                id: webSubscriber.id,
               },
               user_location: {
                 lat: 0,
@@ -260,10 +260,10 @@ describe('BlockService', () => {
       ipAddress: '1.1.1.1',
       agent: 'Chromium',
     });
-    const webSubscriber = await subscriberService.findOne({
+    const webSubscriber = (await subscriberService.findOne({
       foreign_id: 'foreign-id-web-1',
-    });
-    event.setSender(webSubscriber!);
+    }))!;
+    event.setSender(webSubscriber);
 
     const clearMock = jest
       .spyOn(botService, 'handleIncomingMessage')
@@ -278,10 +278,10 @@ describe('BlockService', () => {
             active: true,
             context: {
               user: {
-                first_name: webSubscriber!.first_name,
-                last_name: webSubscriber!.last_name,
+                first_name: webSubscriber.first_name,
+                last_name: webSubscriber.last_name,
                 language: 'en',
-                id: webSubscriber!.id,
+                id: webSubscriber.id,
               },
               user_location: { lat: 0, lon: 0 },
               vars: {},
@@ -314,10 +314,10 @@ describe('BlockService', () => {
       ipAddress: '1.1.1.1',
       agent: 'Chromium',
     });
-    const webSubscriber = await subscriberService.findOne({
+    const webSubscriber = (await subscriberService.findOne({
       foreign_id: 'foreign-id-web-2',
-    });
-    event.setSender(webSubscriber!);
+    }))!;
+    event.setSender(webSubscriber);
     const captured = await botService.processConversationMessage(event);
 
     expect(captured).toBe(false);
diff --git a/api/src/extensions/channels/web/base-web-channel.ts b/api/src/extensions/channels/web/base-web-channel.ts
index 28c49bff..99d2992f 100644
--- a/api/src/extensions/channels/web/base-web-channel.ts
+++ b/api/src/extensions/channels/web/base-web-channel.ts
@@ -236,7 +236,7 @@ export default abstract class BaseWebChannelHandler<
           ...message,
           author: 'chatbot',
           read: true, // Temporary fix as read is false in the bd
-          mid: anyMessage.mid || 'DEFAULT_MID',
+          mid: anyMessage.mid || this.generateId(),
           handover: !!anyMessage.handover,
           createdAt: anyMessage.createdAt,
         });
@@ -621,7 +621,12 @@ export default abstract class BaseWebChannelHandler<
         size: Buffer.byteLength(data.file),
         type: data.type,
       });
-      return attachment;
+
+      if (attachment) {
+        return attachment;
+      } else {
+        throw new Error('Unable to retrieve stored attachment');
+      }
     } catch (err) {
       this.logger.error(
         'Web Channel Handler : Unable to store uploaded file',
@@ -639,7 +644,7 @@ export default abstract class BaseWebChannelHandler<
   async handleWebUpload(
     req: Request,
     res: Response,
-  ): Promise<Attachment | null> {
+  ): Promise<Attachment | null | undefined> {
     try {
       const upload = multer({
         limits: {
@@ -665,7 +670,9 @@ export default abstract class BaseWebChannelHandler<
               reject(new Error('Unable to upload file!'));
             }
 
-            resolve(req.file);
+            if (req.file) {
+              resolve(req.file);
+            }
           });
         },
       );
@@ -678,12 +685,18 @@ export default abstract class BaseWebChannelHandler<
         return null;
       }
 
-      const attachment = await this.attachmentService.store(file, {
-        name: file.originalname,
-        size: file.size,
-        type: file.mimetype,
-      });
-      return attachment;
+      if (file) {
+        const attachment = await this.attachmentService.store(file, {
+          name: file.originalname,
+          size: file.size,
+          type: file.mimetype,
+        });
+        if (attachment) {
+          return attachment;
+        }
+
+        throw new Error('Unable to store uploaded file');
+      }
     } catch (err) {
       this.logger.error(
         'Web Channel Handler : Unable to store uploaded file',
@@ -703,7 +716,7 @@ export default abstract class BaseWebChannelHandler<
   async handleUpload(
     req: Request | SocketRequest,
     res: Response | SocketResponse,
-  ): Promise<Attachment | null> {
+  ): Promise<Attachment | null | undefined> {
     // Check if any file is provided
     if (!req.session.web) {
       this.logger.debug('Web Channel Handler : No session provided');
diff --git a/api/src/extensions/channels/web/wrapper.ts b/api/src/extensions/channels/web/wrapper.ts
index b26cf7ac..094ee5ae 100644
--- a/api/src/extensions/channels/web/wrapper.ts
+++ b/api/src/extensions/channels/web/wrapper.ts
@@ -27,26 +27,31 @@ type WebEventAdapter =
       eventType: StdEventType.unknown;
       messageType: never;
       raw: Web.Event;
+      attachment: never;
     }
   | {
       eventType: StdEventType.read;
       messageType: never;
       raw: Web.StatusReadEvent;
+      attachment: never;
     }
   | {
       eventType: StdEventType.delivery;
       messageType: never;
       raw: Web.StatusDeliveryEvent;
+      attachment: never;
     }
   | {
       eventType: StdEventType.typing;
       messageType: never;
       raw: Web.StatusTypingEvent;
+      attachment: never;
     }
   | {
       eventType: StdEventType.message;
       messageType: IncomingMessageType.message;
       raw: Web.IncomingMessage<Web.IncomingTextMessage>;
+      attachment: never;
     }
   | {
       eventType: StdEventType.message;
@@ -54,11 +59,13 @@ type WebEventAdapter =
         | IncomingMessageType.postback
         | IncomingMessageType.quick_reply;
       raw: Web.IncomingMessage<Web.IncomingPayloadMessage>;
+      attachment: never;
     }
   | {
       eventType: StdEventType.message;
       messageType: IncomingMessageType.location;
       raw: Web.IncomingMessage<Web.IncomingLocationMessage>;
+      attachment: never;
     }
   | {
       eventType: StdEventType.message;
@@ -68,11 +75,9 @@ type WebEventAdapter =
     };
 
 // eslint-disable-next-line prettier/prettier
-export default class WebEventWrapper<N extends ChannelName> extends EventWrapper<
-  WebEventAdapter,
-  Web.Event,
-  N
-> {
+export default class WebEventWrapper<
+  N extends ChannelName,
+> extends EventWrapper<WebEventAdapter, Web.Event, N> {
   /**
    * Constructor : channel's event wrapper
    *
diff --git a/api/src/utils/test/mocks/subscriber.ts b/api/src/utils/test/mocks/subscriber.ts
index 8ec8ee83..490a6bd5 100644
--- a/api/src/utils/test/mocks/subscriber.ts
+++ b/api/src/utils/test/mocks/subscriber.ts
@@ -28,6 +28,8 @@ export const subscriberInstance: Subscriber = {
     name: 'web-channel',
   },
   labels: [],
+  avatar: null,
+  context: {},
   ...modelInstance,
 };
 
diff --git a/api/src/utils/test/sort.ts b/api/src/utils/test/sort.ts
index 6cd91662..28215170 100644
--- a/api/src/utils/test/sort.ts
+++ b/api/src/utils/test/sort.ts
@@ -13,16 +13,20 @@ type TSortProps<T> = {
   order?: 'desc' | 'asc';
 };
 
-type TCreateAt = { createdAt?: string | Date };
+type TCreatedAt = { createdAt?: string | Date };
 
-const sort = <R extends TCreateAt, S, T extends TCreateAt = R & S>({
+const sort = <R extends TCreatedAt, S, T extends TCreatedAt = R & S>({
   row1,
   row2,
   field = 'createdAt',
   order = 'desc',
 }: TSortProps<T>) => (order === 'asc' && row1[field] > row2[field] ? 1 : -1);
 
-export const sortRowsBy = <R extends TCreateAt, S, T extends TCreateAt = R & S>(
+export const sortRowsBy = <
+  R extends TCreatedAt,
+  S,
+  T extends TCreatedAt = R & S,
+>(
   row1: T,
   row2: T,
   field?: keyof T,
diff --git a/api/types/event-emitter.d.ts b/api/types/event-emitter.d.ts
index fadb4d6e..a39d15cf 100644
--- a/api/types/event-emitter.d.ts
+++ b/api/types/event-emitter.d.ts
@@ -93,7 +93,7 @@ declare module '@nestjs/event-emitter' {
       object,
       {
         block: BlockFull;
-        passation: Subscriber | null;
+        passation: Subscriber;
         'fallback-local': BlockFull;
         'fallback-global': EventWrapper<any, any>;
         intervention: Subscriber;