Based on my research, I can help you fix this issue. The key is that Slack requires specific formatting to render markdown properly. Here's how to modify your code: 1. First, you need to tell Slack that you're sending markdown by using the

mrkdwn

type in the message format. Here's the corrected version:

python
slack_webhook_block = SlackWebhook.load("gen3-fleet-health-slack-notifications")
slack_webhook_block.notify({
    "blocks": [
        {
            "type": "section",
            "text": {
                "type": "mrkdwn",
                "text": f"Fleet monitoring summary: {summary_md}"
            }
        }
    ]
})

This approach uses Slack's Block Kit format, which is the recommended way to format messages in Slack. The

mrkdwn

type explicitly tells Slack to interpret the text as markdown. A few important notes: 1. Make sure your markdown follows Slack's markdown syntax, which is slightly different from standard markdown 2. Slack supports a subset of markdown including: - Bold text with

*bold*

- Italic text with

_italic_

- Code blocks with

```

- Lists with • or numbers - Links with

<URL|text>

If you're still having issues after making these changes, you might want to: 1. Double-check your markdown syntax matches Slack's supported format 2. Test the webhook directly using Slack's Block Kit Builder to verify the formatting 3. Make sure your webhook URL is correctly configured in the Prefect block Would you like me to help you format any specific markdown elements you're trying to use?

i got this error -

Unhandled Notification Exception

how do i fix this @Marvin?

The "Unhandled Notification Exception" typically occurs when there's an error in how the message is being sent to Slack, but the error details are being swallowed. Let's modify your code to catch and print the actual error:

python
from prefect.blocks.notifications import SlackWebhook
import json

slack_webhook_block = SlackWebhook.load("gen3-fleet-health-slack-notifications")

try:
    # First, let's try a simple message to test the connection
    response = slack_webhook_block.notify("Test message")
    print(f"Response: {response}")
except Exception as e:
    print(f"Error details: {str(e)}")

If that works, then try your markdown message:

python
try:
    message = {
        "text": f"Fleet monitoring summary: {summary_md}",  # Fallback text
        "blocks": [
            {
                "type": "section",
                "text": {
                    "type": "mrkdwn",
                    "text": f"Fleet monitoring summary: {summary_md}"
                }
            }
        ]
    }
    response = slack_webhook_block.notify(message)
    print(f"Response: {response}")
except Exception as e:
    print(f"Error details: {str(e)}")

This will help us see the actual error message. The issue could be one of several things: 1. Invalid webhook URL: Verify your Slack webhook block is configured correctly:

python
print(slack_webhook_block.url)  # Check if the URL looks valid

2. Message format: Make sure your

summary_md

doesn't contain any characters that need escaping 3. Webhook permissions: Verify the webhook has permission to post in the intended channel Could you run the modified code with error handling and share what error message you get? This will help us pinpoint the exact issue. Also, as a simpler alternative, you could try using plain text first to verify the webhook is working:

python
# Test with plain text first
slack_webhook_block.notify("Simple test message")

If that works, we can then gradually add the markdown formatting back in to identify where the issue occurs.

I see the issue now. There are two different ways to work with Slack in Prefect, and they have different APIs: 1. The built-in

prefect.blocks.notifications.SlackWebhook

2. The separate

prefect-slack

package with

prefect_slack.credentials.SlackWebhook

For your case, since you've already defined the block in Prefect, let's use the built-in version. Here's the correct code:

python
from prefect.blocks.notifications import SlackWebhook

slack_webhook_block = SlackWebhook.load("gen3-fleet-health-slack-notifications")
# For the built-in SlackWebhook, just send the message directly
slack_webhook_block.notify(f"Fleet monitoring summary: {summary_md}")

If you want to use markdown formatting, you can use Slack's mrkdwn syntax in the message directly:

python
message = f"""
*Fleet monitoring summary*
{summary_md}
"""
slack_webhook_block.notify(message)

The built-in

SlackWebhook

block is simpler and doesn't support the full Slack Blocks API. If you need more advanced Slack features, you would need to: 1. Install the separate package:

bash
pip install prefect-slack

2. Re-create your block using the

prefect-slack

package's block type 3. Use that package's more extensive API Would you like me to show you how to set up the more advanced

prefect-slack

version, or would you prefer to stick with the built-in version? The built-in version should work fine for most notification needs, but it has simpler formatting options.

Ah yes - this is actually a limitation of Slack's markdown support, not Prefect itself. Slack's "mrkdwn" format only supports a subset of markdown features, and tables are not one of them. Here are the markdown features that Slack does support: -

*bold*

or

*bold*

-

_italic_

or

*italic*

- ``

code

`` (inline code) -

code blocks

- Bullet lists - Links in format

<URL|text>

- Blockquotes with

>

For tables, you'll need to format them differently to look good in Slack. Here are a few alternatives: 1. Code Block Format (simplest):

python
message = """
*Fleet monitoring summary*

col1 | col2 | col3 1 | 2 | 3 4 | 5 | 6 7 | 8 | 9

"""
slack_webhook_block.notify(message)

2. Using Emoji Bullets and Indentation:

python
message = """
*Fleet monitoring summary*
• Col1: 1 | Col2: 2 | Col3: 3
• Col1: 4 | Col2: 5 | Col3: 6
• Col1: 7 | Col2: 8 | Col3: 9
"""
slack_webhook_block.notify(message)

3. If you need more complex formatting, you would need to switch to using the

prefect-slack

package which supports Slack's Block Kit format. This would allow you to use Slack's native table-like layouts:

python
from prefect_slack import SlackCredentials

# This would require recreating your block with the prefect-slack package
message = {
    "blocks": [
        {
            "type": "section",
            "text": {
                "type": "mrkdwn",
                "text": "*Fleet monitoring summary*"
            }
        },
        {
            "type": "section",
            "fields": [
                {"type": "mrkdwn", "text": "*Col1*\n1\n4\n7"},
                {"type": "mrkdwn", "text": "*Col2*\n2\n5\n8"},
                {"type": "mrkdwn", "text": "*Col3*\n3\n6\n9"}
            ]
        }
    ]
}

For your current setup using the built-in

prefect.blocks.notifications.SlackWebhook

, I'd recommend either: 1. Use the code block format if you want to preserve the table-like appearance 2. Use the bullet point format if you want it to look more native in Slack 3. Consider switching to

prefect-slack

if you need more advanced formatting frequently Which approach would you prefer to try?

Yes! Even with the basic SlackWebhook, you can make messages look pretty using Slack's supported formatting. Here are some creative approaches: 1. Using Emojis and Headers:

python
message = """
:clipboard: *Fleet Monitoring Summary* :bar_chart:
--------------------------------
:green_circle: *Success Metrics*
• Completed: 25 flows
• Average Duration: 45s

:warning: *Attention Needed*
• Failed: 2 flows
• Pending: 3 flows
"""
slack_webhook_block.notify(message)

2. Using Quote Blocks and Dividers:

python
message = """
*:mag: Fleet Monitoring Summary*
>*Status Overview*
>:white_check_mark: Healthy: 80%
>:warning: Warning: 15%
>:x: Critical: 5%

*Detailed Metrics*
• CPU Usage: `85%`
• Memory: `4.2GB/8GB`
• Active Workers: `12`
"""
slack_webhook_block.notify(message)

3. Using Unicode Characters for Visual Structure:

python
message = """
📊 *Fleet Monitoring Summary* 📊
━━━━━━━━━━━━━━━━━━━━━━━━━━━━
🔷 *Performance*
   • Throughput: 1000 tasks/hour
   • Latency: 250ms average

🔶 *Resources*
   • Workers: 5 active
   • Queue: 25 pending
"""
slack_webhook_block.notify(message)

4. Combining Code Blocks with Formatted Sections:

python
message = """
:rocket: *Fleet Monitoring Summary* :rocket:

*Current Status*

Service | Status | Load ---------|--------|------ API | ✅ | 75% Workers | ✅ | 60% Queue | ⚠️ | 85%

:information_source: *Additional Details*
• Last Updated: 10:00 AM UTC
• Environment: Production
• Region: US-East
"""
slack_webhook_block.notify(message)

5. Using Indentation and Symbols:

python
message = """
🎯 *Fleet Monitoring Summary*
┌─────────────────────────┐
│ *System Health*         │
├─────────────────────────┤
│ ✨ Performance: Good    │
│ 📈 Uptime: 99.9%       │
│ 🔄 Active Jobs: 42     │
└─────────────────────────┘

*Quick Stats*
⚡️ Processing: 500 tasks/min
🔋 CPU Load: 65%
📊 Memory Usage: 75%
"""
slack_webhook_block.notify(message)

Key formatting tips: 1. Use emojis strategically (

:emoji_name:

) to add visual cues 2. Utilize

*bold*

for headers and important information 3. Use

>

for quote blocks to highlight important sections 4. Add line breaks and spacing for readability 5. Use unicode characters like

│

,

─

,

•

for structure 6. Combine code blocks (```) for fixed-width formatting 7. Use emoji bullets for lists (🔹, 🔸, etc.) Would you like me to help you format your specific content in any of these styles? Just share what kind of information you're trying to display, and I can help you make it visually appealing! Also, if you need even more advanced formatting (like interactive buttons or color-coded sections), we could look into switching to the

prefect-slack

package which supports Slack's Block Kit format.