"Sorry, this didn't work" error with working Message Shortcut

Hello Slack! I am building Slack app according to your documentation (https://api.slack.com/surfaces/modals/using#modal_response_url) and I have an issue with Slack Message Shortcut. It works almost fine, when I create modal.open - it opens modal window with proper elements. But in Slack application window appears Error in lower right corner “Sorry, this didn’t work. Try again?”. Furthermore everything works fine and I don’t get any errors in logs on my server side. I wondering how to remove this error message. Do I need to send any additional response to Slack server when I execute message shortcut?

In mobile ios application everything works without any additional Errors.

Preview: https://imgur.com/Ag3KcBq

Reproducible in:

def form_and_push_msg_modal(payload):
    # Forming view
    payload = {
        "token": slack_token,
        "trigger_id": payload["trigger_id"],
        "view": view_str,
    }
    r = requests.post("https://slack.com/api/views.open", data=payload, timeout=1)
    r.raise_for_status()

if payload["type"] == "message_action":
    form_and_push_msg_modal(payload)

The Slack SDK version

slackclient==2.8.2

Python runtime version

Python 3.8.2

OS info

Linux semu 5.4.0-47-generic #51-Ubuntu SMP Fri Sep 4 19:50:52 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

Steps to reproduce:

1. Parse with any library request from Slack if payload[“type”] == “message_action”:
2. Return any result, even empty body return

Expected result:

Same as I get, but Error message doesn’t appear in slack application.

Actual result:

INFO:     52.23.240.52:0 - "POST /slack/interactions HTTP/1.1" 200 OK
[INFO] slack.reactions (Source: slack/reactions.py:61, Time: 2020-09-17 02:53:13,226) - Slack conversation info response
[INFO] slack.interactions (Source: slack/interactions.py:663, Time: 2020-09-17 02:53:14,376) - SHORTCUT: create-msg

Requirements

For general questions/issues about Slack API platform or its server-side, could you submit questions at https://my.slack.com/help/requests/new instead. 🙇

Please read the Contributing guidelines and Code of Conduct before creating this issue or pull request. By submitting, you are agreeing to those rules.

[seratch]

Modifying the lines should work for you.

diff --git a/integration_tests/samples/basic_usage/views.py b/integration_tests/samples/basic_usage/views.py
index 49ccbb2..5e4de6e 100644
--- a/integration_tests/samples/basic_usage/views.py
+++ b/integration_tests/samples/basic_usage/views.py
@@ -39,8 +39,8 @@ def slack_app():
     if "payload" in request.form:
         payload = json.loads(request.form["payload"])
 
-        if payload["type"] == "shortcut" \
-            and payload["callback_id"] == "open-modal-shortcut":
+        if payload["type"] == "message_action" \
+            and payload["callback_id"] == "(your own callback id here)":
             # Open a new modal by a global shortcut
             try:
                 api_response = client.views_open(

Just in case, I verified this sample works with message shortcuts. I didn’t see any issues.

If your views.open API calls result in {'ok': False, 'error': 'invalid_arguments', 'response_metadata': {'messages': ['[ERROR] invalid trigger_id [json-pointer:/trigger_id]']}}, make sure your access token (=SLACK_API_TOKEN in this sample).

[seratch]

It’s great to know you’ve figured out the cause. Let me close this issue now.