[BUG] Slack Notifications - [no preview available]

[bslatyer]

📑 I have found these related issues/pull requests

N/A

🛡️ Security Policy

• I agree to have read this project Security Policy

Description

Slack Notifications worked as expected in the Uptime Kuma 1.x.x and displayed a notification preview correctly.

Now in Uptime Kuma 2.x.x, Slack Notifications do not work as expected and now display [no preview available]

👟 Reproduction steps

Any Uptime Kuma POST Request to a Slack webhook causes this issue

👀 Expected behavior

Slack is meant to display a brief Notification Preview

😓 Actual Behavior

Slack doesn't display a notification preview

🐻 Uptime-Kuma Version

2.0.0-beta.1

💻 Operating System and Arch

Debian 12.9 - ARM64

🌐 Browser

Safari 18.3 (20620.2.4.11.4)

🖥️ Deployment Environment

• Runtime: Docker 27.5.0
• Database: SQLite
• Filesystem used to store the database on: EXT4 on an NVMe
• Number of Monitors: 42

📝 Relevant log output

2025-01-22T19:41:12+11:00 [MONITOR] ERROR: Cannot send notification to Slack
2025-01-22T19:41:12+11:00 [MONITOR] ERROR: Error: Error: AxiosError: Request failed with status code 400 invalid_attachments
    at Slack.throwGeneralAxiosError (/app/server/notification-providers/notification-provider.js:69:15)
    at Slack.send (/app/server/notification-providers/slack.js:172:18)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async Monitor.sendNotification (/app/server/model/monitor.js:1343:21)
    at async beat (/app/server/model/monitor.js:925:21)
    at async Timeout.safeBeat [as _onTimeout] (/app/server/model/monitor.js:1010:17)