diff --git a/.github/workflows/doctests.yml b/.github/workflows/doctests.yml
index 9fc74e2e6c..8a8968be52 100644
--- a/.github/workflows/doctests.yml
+++ b/.github/workflows/doctests.yml
@@ -74,5 +74,5 @@ jobs:
           CI_SLACK_CHANNEL_ID_DAILY: ${{ secrets.CI_SLACK_CHANNEL_ID_DAILY_DOCS }}
           CI_SLACK_CHANNEL_DUMMY_TESTS: ${{ secrets.CI_SLACK_CHANNEL_DUMMY_TESTS }}
         run: |
-          pip install slack_sdk
+          pip install slack_sdk==3.18.1
           python utils/notification_service_doc_tests.py
diff --git a/.github/workflows/self-nightly-scheduled.yml b/.github/workflows/self-nightly-scheduled.yml
index 371620c543..78b14463b3 100644
--- a/.github/workflows/self-nightly-scheduled.yml
+++ b/.github/workflows/self-nightly-scheduled.yml
@@ -233,5 +233,5 @@ jobs:
         # We pass `needs.setup.outputs.matrix` as the argument. A processing in `notification_service.py` to change
         # `models/bert` to `models_bert` is required, as the artifact names use `_` instead of `/`.
         run: |
-          pip install slack_sdk
+          pip install slack_sdk==3.18.1
           python utils/notification_service.py "${{ needs.setup.outputs.matrix }}"
diff --git a/.github/workflows/self-past.yml b/.github/workflows/self-past.yml
index b3871dc92f..c977689977 100644
--- a/.github/workflows/self-past.yml
+++ b/.github/workflows/self-past.yml
@@ -180,7 +180,7 @@ jobs:
         # We pass `needs.setup.outputs.matrix` as the argument. A processing in `notification_service.py` to change
         # `models/bert` to `models_bert` is required, as the artifact names use `_` instead of `/`.
         run: |
-          pip install slack_sdk
+          pip install slack_sdk==3.18.1
           python utils/notification_service.py "${{ needs.setup.outputs.matrix }}"
 
       # Upload complete failure tables, as they might be big and only truncated versions could be sent to Slack.
diff --git a/.github/workflows/self-push.yml b/.github/workflows/self-push.yml
index d0efae8b47..dd1222609d 100644
--- a/.github/workflows/self-push.yml
+++ b/.github/workflows/self-push.yml
@@ -527,5 +527,5 @@ jobs:
         # We pass `needs.setup.outputs.matrix` as the argument. A processing in `notification_service.py` to change
         # `models/bert` to `models_bert` is required, as the artifact names use `_` instead of `/`.
         run: |
-          pip install slack_sdk
+          pip install slack_sdk==3.18.1
           python utils/notification_service.py "${{ needs.setup.outputs.matrix }}"
diff --git a/.github/workflows/self-scheduled.yml b/.github/workflows/self-scheduled.yml
index 323ca5eb54..4d8feba32a 100644
--- a/.github/workflows/self-scheduled.yml
+++ b/.github/workflows/self-scheduled.yml
@@ -358,5 +358,5 @@ jobs:
         # We pass `needs.setup.outputs.matrix` as the argument. A processing in `notification_service.py` to change
         # `models/bert` to `models_bert` is required, as the artifact names use `_` instead of `/`.
         run: |
-          pip install slack_sdk
+          pip install slack_sdk==3.18.1
           python utils/notification_service.py "${{ needs.setup.outputs.matrix }}"