An "invalid_attachments" error is thrown when blocks are included within a MessageAttachment object

Description

I’m calling client.chat.postMessage and passing in an array of message attachments. Without setting the blocks property for one of the elements of the array, the message posts as expected and includes the attachments.

However, if I set the blocks property in one of these attachment elements, an “invalid_attachments” error is thrown.

The full stack trace can be found at the bottom of this issue.

What type of issue is this? (place an x in one of the [ ])

• bug
• enhancement (feature request)
• question
• documentation related
• example code related
• testing related
• discussion

Requirements (place an x in each of the [ ])

• I’ve read and understood the Contributing guidelines and have done my best effort to follow them.
• I’ve read and agree to the Code of Conduct.
• I’ve searched for any related issues and avoided creating a duplicate issue.

---

Bug Report

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Reproducible in:

package version: @slack/bolt 2.5.0

node version: 13.10.1

OS version(s): macOS Mojave Version 10.14.6

Steps to reproduce:

1. Here’s an example code block which uses placeholder values:

const testSectionBlock: SectionBlock = {
    type: "section",
    text: {
        type: "mrkdwn",
        text: "Section block text"
    }
};

const blocks: KnownBlock[] = [testSectionBlock];

const attachments: MessageAttachment[] = [
    {
        text: "Message attachment text",
        callback_id: "test_callback_id",
        color: "#88D8B0",
        blocks // if you don't include this argument, it works
    }
];

const response: any = await client.chat.postMessage({
    text: "Outer text"
    attachments,
    channel,
    token,
});

Expected result:

What you expected to happen

Here’s a screenshot of how the message looks without the blocks included: It should be able to include the blocks within the message attachments.

Actual result:

What actually happened

Error: An API error occurred: invalid_attachments

^ Prevents the message from being posted

Attachments:

Logs, screenshots, screencast, sample project, funny gif, etc.

Notes:

• In the Slack Node SDK index file, MessageAttachment can include an optional blocks property.
• There’s documentation which shows an example of blocks being included in an attachments field.
• In the Slack Java SDK, there are test cases asserting that “invalid_blocks” should be thrown. Although in the linked issue, it’s stated that blocks within attachments should be supported.

Logs:

Error: An API error occurred: invalid_attachments
    at Object.platformErrorFromResult (/<REDACTED>/node_modules/@slack/web-api/dist/errors.js:51:33)
    at WebClient.apiCall (/<REDACTED>/node_modules/@slack/web-api/dist/WebClient.js:156:28)
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
    at async /<REDACTED>.js:112:30
    at async Array.<anonymous> (<REDACTED>/node_modules/@slack/bolt/dist/middleware/builtin.js:203:9)
    at async Array.exports.onlyCommands <REDACTED>/node_modules/@slack/bolt/dist/middleware/builtin.js:41:5) {
  code: 'slack_webapi_platform_error',
  data: {
    ok: false,
    error: 'invalid_attachments',
    response_metadata: {
      messages: [ '[ERROR] invalid_keys' ],
      scopes: [
        'channels:history',
        'channels:join',
        'chat:write',
        'commands',
        'users:read',
        'users:read.email',
        'channels:read',
        'im:write',
        'channels:manage',
        'groups:write',
        'mpim:write'
      ],
      acceptedScopes: [ 'chat:write' ]
    }
  }
}

[victoria-miltcheva]

Does removing text / callback_id solve your issue? You’ll lose access to callback_id (I assume for a legacy button or menu) but you could likely take advantage of action_id in blocks.

Yes, removing these fields solved my issue. I was also able to use action_id in blocks for the button and my action middleware was triggered when it was clicked.

Thanks again for your help and for submitting a color feature request for Block Kit 👍 .

[alosipov]

Yo Michael 🤝 @mwbrooks ! That helps indeed! Thank you very much! Broke my head on this ) :happy: