diff --git a/connectors/migrations/20230725_slack_channel_permissions.ts b/connectors/migrations/20230725_slack_channel_permissions.ts
index 4097e4ea80acb..d8a0e6db1aa23 100644
--- a/connectors/migrations/20230725_slack_channel_permissions.ts
+++ b/connectors/migrations/20230725_slack_channel_permissions.ts
@@ -26,7 +26,7 @@ async function main() {
     );
 
     const accessToken = await getAccessToken(c.connectionId);
-    const channelsInSlack = await getChannels(accessToken);
+    const channelsInSlack = await getChannels(accessToken, true);
     const channelIdsInSlackSet = new Set(
       channelsInSlack.map((c) => c.id).filter((id) => id)
     );
diff --git a/connectors/src/api/webhooks/webhook_slack.ts b/connectors/src/api/webhooks/webhook_slack.ts
index d67c8e65c4eea..c0d4d0f847159 100644
--- a/connectors/src/api/webhooks/webhook_slack.ts
+++ b/connectors/src/api/webhooks/webhook_slack.ts
@@ -6,7 +6,6 @@ import {
   getBotUserIdMemoized,
 } from "@connectors/connectors/slack/temporal/activities";
 import {
-  launchSlackBotJoinedWorkflow,
   launchSlackSyncOneMessageWorkflow,
   launchSlackSyncOneThreadWorkflow,
 } from "@connectors/connectors/slack/temporal/client";
@@ -17,7 +16,7 @@ import {
   SlackChannel,
   SlackConfiguration,
 } from "@connectors/lib/models";
-import { Err, Ok } from "@connectors/lib/result";
+import { Ok } from "@connectors/lib/result";
 import logger from "@connectors/logger/logger";
 import { apiError, withLogging } from "@connectors/logger/withlogging";
 
@@ -327,76 +326,6 @@ const _webhookSlackAPIHandler = async (
         break;
       }
 
-      /**
-       * `member_joined_channel` handler.
-       */
-      case "member_joined_channel": {
-        if (!req.body.event?.channel || !req.body.event?.user) {
-          return apiError(req, res, {
-            api_error: {
-              type: "invalid_request_error",
-              message:
-                "Missing channel or user in request body for member_joined_channel event",
-            },
-            status_code: 400,
-          });
-        }
-        const channel = req.body.event.channel;
-        const user = req.body.event.user;
-        let err: Error | null = null;
-
-        const results = await Promise.all(
-          slackConfigurations.map((c) =>
-            (async (): Promise<Err<Error> | Ok<string>> => {
-              const connector = await Connector.findByPk(c.connectorId);
-              if (!connector) {
-                return new Err(
-                  new Error(`Connector ${c.connectorId} not found`)
-                );
-              }
-
-              const slackAccessToken = await getAccessToken(
-                connector.connectionId
-              );
-              const myUserId = await getBotUserIdMemoized(slackAccessToken);
-              if (myUserId !== user) {
-                return new Ok("");
-              }
-              return await launchSlackBotJoinedWorkflow(
-                c.connectorId.toString(),
-                channel
-              );
-            })()
-          )
-        );
-        for (const r of results) {
-          if (r.isErr()) {
-            err = r.error;
-          }
-        }
-
-        if (err) {
-          return apiError(req, res, {
-            api_error: {
-              type: "internal_server_error",
-              message: err.message,
-            },
-            status_code: 500,
-          });
-        } else {
-          logger.info(
-            {
-              type: req.body.event.type,
-              channel: req.body.event.channel,
-              user: req.body.event.user,
-            },
-            `Successfully processed Slack Webhook`
-          );
-          return res.status(200).send();
-        }
-        break;
-      }
-
       /**
        * `channel_left`, `channel_deleted` handler.
        */
diff --git a/connectors/src/connectors/slack/bot.ts b/connectors/src/connectors/slack/bot.ts
index 4ba33a5ff3f63..f9b4e6a65a6bf 100644
--- a/connectors/src/connectors/slack/bot.ts
+++ b/connectors/src/connectors/slack/bot.ts
@@ -351,7 +351,6 @@ async function botAnswerMessage(
   }
   let conversation: ConversationType | undefined = undefined;
   let userMessage: UserMessageType | undefined = undefined;
-
   if (lastSlackChatBotMessage?.conversationId) {
     if (buildContentFragmentRes.value) {
       const contentFragmentRes = await dustAPI.postContentFragment({
@@ -609,7 +608,7 @@ async function makeContentFragment(
   startingAtTs: string | null,
   connector: Connector
 ) {
-  const slackChannelPromise = slackClient.conversations.info({
+  const slackChannelPromise = await slackClient.conversations.info({
     channel: channelId,
   });
   let allMessages: Message[] = [];
diff --git a/connectors/src/connectors/slack/index.ts b/connectors/src/connectors/slack/index.ts
index 19bc61b53692a..3c3e2b919a739 100644
--- a/connectors/src/connectors/slack/index.ts
+++ b/connectors/src/connectors/slack/index.ts
@@ -1,6 +1,5 @@
 import { WebClient } from "@slack/web-api";
 import PQueue from "p-queue";
-import { Op } from "sequelize";
 
 import { ConnectorPermissionRetriever } from "@connectors/connectors/interface";
 import {
@@ -30,7 +29,12 @@ import {
   ConnectorResource,
 } from "@connectors/types/resources";
 
-import { getAccessToken, getSlackClient } from "./temporal/activities";
+import {
+  getAccessToken,
+  getChannels,
+  getSlackClient,
+  joinChannel,
+} from "./temporal/activities";
 
 const { NANGO_SLACK_CONNECTOR_ID, SLACK_CLIENT_ID, SLACK_CLIENT_SECRET } =
   process.env;
@@ -169,15 +173,19 @@ export async function updateSlackConnector(
   const updateParams: Parameters<typeof c.update>[0] = {};
 
   if (connectionId) {
-    const newConnectionRes = await nango_client().getConnection(
-      NANGO_SLACK_CONNECTOR_ID,
-      connectionId,
-      false,
-      false
-    );
-    const newTeamId = newConnectionRes?.team?.id || null;
+    const accessToken = await getAccessToken(connectionId);
+    const slackClient = await getSlackClient(accessToken);
+    const teamInfoRes = await slackClient.team.info();
+    if (!teamInfoRes.ok || !teamInfoRes.team?.id) {
+      return new Err({
+        error: {
+          message: "Can't get the Slack team information.",
+        },
+      });
+    }
 
-    if (!newTeamId || newTeamId !== currentSlackConfig.slackTeamId) {
+    const newTeamId = teamInfoRes.team.id;
+    if (newTeamId !== currentSlackConfig.slackTeamId) {
       return new Err({
         error: {
           type: "connector_oauth_target_mismatch",
@@ -353,20 +361,40 @@ export async function retrieveSlackConnectorPermissions({
       break;
   }
 
-  const slackChannels = await SlackChannel.findAll({
-    where: filterPermission
-      ? {
-          connectorId: connectorId,
-          permission: { [Op.or]: permissionToFilter },
-        }
-      : {
-          connectorId: connectorId,
-        },
-    order: [
-      ["createdAt", "DESC"],
-      ["slackChannelName", "ASC"],
-    ],
-  });
+  const slackChannels: {
+    slackChannelId: string;
+    slackChannelName: string;
+    permission: ConnectorPermission;
+  }[] = [];
+
+  const accessToken = await getAccessToken(c.connectionId);
+  const remoteChannels = await getChannels(accessToken, false);
+  for (const remoteChannel of remoteChannels) {
+    if (!remoteChannel.id || !remoteChannel.name) {
+      continue;
+    }
+
+    const permissions =
+      (
+        await SlackChannel.findOne({
+          where: {
+            connectorId: connectorId,
+            slackChannelId: remoteChannel.id,
+          },
+        })
+      )?.permission || (remoteChannel.is_member ? "write" : "none");
+
+    if (
+      permissionToFilter.length === 0 ||
+      permissionToFilter.includes(permissions)
+    ) {
+      slackChannels.push({
+        slackChannelId: remoteChannel.id,
+        slackChannelName: remoteChannel.name,
+        permission: permissions,
+      });
+    }
+  }
 
   const resources: ConnectorResource[] = slackChannels.map((ch) => ({
     provider: "slack",
@@ -427,17 +455,49 @@ export async function setSlackConnectorPermissions(
 
   let shouldGarbageCollect = false;
   for (const [id, permission] of Object.entries(permissions)) {
-    const channel = channels[id];
+    let channel = channels[id];
+    const slackAccessToken = await getAccessToken(connector.connectionId);
+    const slackClient = await getSlackClient(slackAccessToken);
     if (!channel) {
-      logger.error(
-        { connectorId, channelId: id },
-        "Could not find channel in DB"
-      );
-      continue;
+      const remoteChannel = await slackClient.conversations.info({
+        channel: id,
+      });
+      if (!remoteChannel.ok || !remoteChannel.channel?.name) {
+        logger.error(
+          {
+            connectorId,
+            channelId: id,
+            error: remoteChannel.error,
+          },
+          "Could not get the Slack channel information"
+        );
+        return new Err(
+          new Error("Could not get the Slack channel information.")
+        );
+      }
+      const joinRes = await joinChannel(connectorId, id);
+      if (joinRes === "cant_join") {
+        return new Err(
+          new Error(
+            `Our Slack bot (@Dust) was not able to join the Slack channel #${remoteChannel.channel.name}. Please re-authorize Slack or invite @Dust to #${remoteChannel.channel.name} manually.`
+          )
+        );
+      }
+      const slackChannel = await SlackChannel.create({
+        connectorId: connectorId,
+        slackChannelId: id,
+        slackChannelName: remoteChannel.channel.name,
+        permission: "none",
+      });
+      channels[id] = slackChannel;
+      channel = slackChannel;
     }
 
     promises.push(
       q.add(async () => {
+        if (!channel) {
+          return;
+        }
         const oldPermission = channel.permission;
         if (oldPermission === permission) {
           return;
@@ -451,6 +511,16 @@ export async function setSlackConnectorPermissions(
           ["read", "read_write"].includes(permission)
         ) {
           // handle read permission enabled
+          const joinChannelRes = await joinChannel(
+            connectorId,
+            channel.slackChannelId
+          );
+          if (joinChannelRes === "cant_join") {
+            throw new Error(
+              `Our Slack bot (@Dust) was not able to join the Slack channel #${channel.slackChannelName}. Please re-authorize Slack or invite @Dust to #${channel.slackChannelName} manually.`
+            );
+          }
+
           const res = await launchSlackBotJoinedWorkflow(
             connectorId.toString(),
             channel.slackChannelId
diff --git a/connectors/src/connectors/slack/temporal/activities.ts b/connectors/src/connectors/slack/temporal/activities.ts
index d5716110f90b3..d78d2ab103151 100644
--- a/connectors/src/connectors/slack/temporal/activities.ts
+++ b/connectors/src/connectors/slack/temporal/activities.ts
@@ -25,7 +25,12 @@ import {
   upsertToDatasource,
 } from "@connectors/lib/data_sources";
 import { WorkflowError } from "@connectors/lib/error";
-import { SlackChannel, SlackMessages } from "@connectors/lib/models";
+import {
+  Connector,
+  ModelId,
+  SlackChannel,
+  SlackMessages,
+} from "@connectors/lib/models";
 import { getAccessTokenFromNango } from "@connectors/lib/nango_helpers";
 import {
   reportInitialSyncProgress,
@@ -56,7 +61,8 @@ const NETWORK_REQUEST_TIMEOUT_MS = 30000;
  */
 
 export async function getChannels(
-  slackAccessToken: string
+  slackAccessToken: string,
+  joinedOnly: boolean
 ): Promise<Channel[]> {
   const client = getSlackClient(slackAccessToken);
   const allChannels = [];
@@ -79,8 +85,10 @@ export async function getChannels(
       );
     }
     for (const channel of c.channels) {
-      if (channel && channel.id && channel.is_member) {
-        allChannels.push(channel);
+      if (channel && channel.id) {
+        if (!joinedOnly || channel.is_member) {
+          allChannels.push(channel);
+        }
       }
     }
   } while (nextCursor);
@@ -119,6 +127,48 @@ interface SyncChannelRes {
   weeksSynced: Record<number, boolean>;
 }
 
+export async function joinChannel(
+  connectorId: ModelId,
+  channelId: string
+): Promise<"ok" | "already_joined" | "cant_join"> {
+  const connector = await Connector.findByPk(connectorId);
+  if (!connector) {
+    throw new Error(`Connector ${connectorId} not found`);
+  }
+  const accessToken = await getAccessToken(connector.connectionId);
+  const client = getSlackClient(accessToken);
+  try {
+    const channelInfo = await client.conversations.info({ channel: channelId });
+    if (channelInfo.channel?.is_member) {
+      return "already_joined";
+    }
+    const joinRes = await client.conversations.join({ channel: channelId });
+    if (joinRes.ok) {
+      return "ok";
+    } else {
+      return "already_joined";
+    }
+  } catch (e) {
+    const slackError = e as CodedError;
+    if (slackError.code === ErrorCode.PlatformError) {
+      const platformError = slackError as WebAPIPlatformError;
+      if (platformError.data.error === "missing_scope") {
+        logger.info(
+          {
+            channelId,
+            connectorId,
+          },
+          "Could not join channel because of a missing scope. User need to re-authorize it's Slack connection to get the channels:join scope."
+        );
+        return "cant_join";
+      }
+      throw e;
+    }
+  }
+
+  return "cant_join";
+}
+
 export async function syncChannel(
   slackAccessToken: string,
   channelId: string,
@@ -858,7 +908,7 @@ export async function getChannelsToGarbageCollect(
   );
 
   const remoteChannels = new Set(
-    (await getChannels(slackAccessToken))
+    (await getChannels(slackAccessToken, true))
       .filter((c) => c.id)
       .map((c) => c.id as string)
   );
diff --git a/connectors/src/connectors/slack/temporal/workflows.ts b/connectors/src/connectors/slack/temporal/workflows.ts
index 833d98f0d4fa9..bfc9e6a178c8b 100644
--- a/connectors/src/connectors/slack/temporal/workflows.ts
+++ b/connectors/src/connectors/slack/temporal/workflows.ts
@@ -27,6 +27,7 @@ const {
   reportInitialSyncProgressActivity,
   getChannelsToGarbageCollect,
   deleteChannel,
+  joinChannel,
   deleteChannelsFromConnectorDb,
 } = proxyActivities<typeof activities>({
   startToCloseTimeout: "10 minutes",
@@ -52,7 +53,7 @@ export async function workspaceFullSync(
 ): Promise<void> {
   const slackAccessToken = await getAccessToken(nangoConnectionId);
   await fetchUsers(slackAccessToken, connectorId);
-  const channels = await getChannels(slackAccessToken);
+  const channels = await getChannels(slackAccessToken, true);
   let i = 0;
   for (const channel of channels) {
     if (!channel.id || !channel.name) {
@@ -88,6 +89,7 @@ export async function syncOneChannel(
   fromTs: number | null
 ) {
   console.log(`Syncing channel ${channelName} (${channelId})`);
+  await joinChannel(parseInt(connectorId, 10), channelId);
 
   const slackAccessToken = await getAccessToken(nangoConnectionId);
   let messagesCursor: string | undefined = undefined;
diff --git a/front/components/ConnectorPermissionsModal.tsx b/front/components/ConnectorPermissionsModal.tsx
index d4bd939e90fd3..45d891e7dcc20 100644
--- a/front/components/ConnectorPermissionsModal.tsx
+++ b/front/components/ConnectorPermissionsModal.tsx
@@ -122,7 +122,8 @@ export default function ConnectorPermissionsModal({
         );
 
         if (!r.ok) {
-          window.alert("An unexpected error occurred");
+          const error: { error: { message: string } } = await r.json();
+          window.alert(error.error.message);
         }
 
         await mutate(
diff --git a/front/pages/api/w/[wId]/data_sources/[name]/managed/permissions/index.ts b/front/pages/api/w/[wId]/data_sources/[name]/managed/permissions/index.ts
index 587abccdb043c..19539fbe376cf 100644
--- a/front/pages/api/w/[wId]/data_sources/[name]/managed/permissions/index.ts
+++ b/front/pages/api/w/[wId]/data_sources/[name]/managed/permissions/index.ts
@@ -182,7 +182,7 @@ async function handler(
           status_code: 500,
           api_error: {
             type: "internal_server_error",
-            message: `An error occurred while setting the data source permissions.`,
+            message: connectorsRes.error.error.message,
           },
         });
       }