Notification are send in text without interpretation to Slack

[searchjaunt]

As of version v0.50.29. the feed to Slack looks like

All worked fine with previous versions:

Version
v0.50.29

How did you install?

Docker

To Reproduce
It happen with all sites. It doesn't matter what the filters, request type, etc are. All URLs behave the same from now.

example URL:
https://changedetection.io/CHANGELOG.txt

general notification body:
🔀 <{{diff_url}}|Overzicht van de wijzigingen>
🌐 <{{watch_url}}|Originele website>

general Notification format:
plain text

Expected behavior

[dgtlmoon]

@searchjaunt i'm completely confused, you start off the issue with screenshots of sending some HTML document following "http://timlejamaiscontent.be/" webpage, then you talk about plaintext CHANGELOG.txt ?

[searchjaunt]

Hi,
http://timlejamaiscontent.be/ is the server where changedetection runs on.
"Overzicht van de wijzigingen" is the link to this server in order to see the change log changedetection has made
"Originele site" is the site that has been monitored.
As the issue is for all sites, with all kind of filters and fetch methods, I gave the simpliest example for the watch that has been defined for https://changedetection.io/CHANGELOG.txt where all is pretty standard.
Pls let me know if anything else needs to be calrified.

[dgtlmoon]

Please try 0.50.30 in a few minutes once it's built and tell me if it resolves this!

[searchjaunt]

Hi,

I've installed 0.50.30 and I'm afraid the issue remains:

The first attempt was with text as format, the second markdown

I reverted to 0.50.28 and did the same test

The title difference is caused by the fact that the first is a test notification and the second a real one.

[dgtlmoon]

@searchjaunt It works perfectly.. atleast here.. Do not use Markdown to HTML, it will make HTML

I tried using the https:// type hook and the slack:// bot

in the case of slack bot, I couldnt understand the slack UI for configuring the bot, but i can see that it does NOT send any HTML when I select 'plaintext' option

2025/10/25 09:52:07,000 - SENDING - null
b'{"ok":false,"error":"channel_not_found"}'
2025-10-25 09:52:07,940 - DEBUG - Response Details:
2025-10-25 09:52:07,940 - WARNING - Failed to send to Slack: error=200.
2025-10-25 09:52:07,751 - DEBUG - Slack Payload: {'username': 'changedetection.io', 'mrkdwn': False, 'attachments': [{'title': 'some change', 'text': '🔀 <https://mytesite.com/diff/f1a0b2aa-3ab0-4b1c-ba4c-488e9582b513|Overzicht van de wijzigingen>\n🌐 <https://changedetection.io/time.php|Originele website>', 'color': '#3AA3E3', 'footer_icon': 'https://github.com/caronc/apprise/raw/master/apprise/assets/themes/default/apprise-info-72x72.png', 'footer': 'changedetection.io', 'ts': 1761378727.7518115}], 'icon_url': 'https://github.com/caronc/apprise/raw/master/apprise/assets/themes/default/apprise-info-72x72.png', 'channel': '#general'}
2025-10-25 09:52:07,751 - DEBUG - Slack POST URL: https://slack.com/api/chat.postMessage (cert_verify=True)
2025-10-25 09:52:07,751 - DEBUG - Loaded Slack URL: slack://x...l/%23general/?image=yes&footer=yes&timestamp=yes&blocks=no&format=text&overflow=upstream

Main settings

🔀 <{{diff_url}}|Overzicht van de wijzigingen>
🌐 <{{watch_url}}|Originele website>

Notification URL

https://hooks.slack.com/services/T09NZBE2QSV/xxxxx/xxxxxx

here is a test in slack

here is a test in discord

The first attempt was with text as format, the second markdown

The markdown option is clearly labeled as Markdown to HTML, so don't use that one, it will generate HTML.

---

Here is what shows when I select HTML and HTML Color as the output (which is wrong I know, but i want to compare)

Here is Markdown to HTML

[dgtlmoon]

Closing for now, i cannot reproduce it or there is some detail missing

[dgtlmoon]

Moved to discussions for now, it all works perfect after about an hour of testing on my end

[searchjaunt]

It seems that the &blocks=yes in the Slack URL is causing the issue.
Removing it, shows things as expected. So my guess would be that since 0.5.29 another version of apprise is used, which is stricter on things.
So that would mean that I need to remove &blocks=yes for > 500 watches. :-(
Suggestions and what would the quickest and safest way to do so are welcome.

[dgtlmoon]

What does blocks=yes do ?

Suggestions and what would the quickest and safest way to do so are welcome.

shut down changedetection, edit the url-watches.json with a text editor (search/replace)

[searchjaunt]

In Slack’s API:

• The term Blocks refers to structured, rich message elements, defined as JSON objects in the Block Kit system.
• Each block can contain text, buttons, sections, or dividers.
• Messages that use blocks must include a top-level "blocks": [...] property instead of (or in addition to) the usual "text": "..." field.​
• So, conceptually, blocks=yes would tell the message generator to use Slack’s Block Kit formatting instead of plain text — producing visual layouts or interactive components.

It seems, in reality, Apprise’s Slack adapter:

• Sends only simple "text" payloads to Slack’s webhook endpoint.
• Does not include any "blocks" property.
• Ignores or strips unrecognized query parameters such as blocks=yes.

Anyway I've changed the url-watches.json and it does seem to work again as before

[dgtlmoon]

Strangely I hit the same sorta limitation with apprise's discord plugin, it tends to hardcode a lot of 'behaviour' into a apprise layout of things.. so hmm.. like I said, i need to see exactly what you're doing/sending, complete slack URL etc, maybe access to slack too?

[searchjaunt]

As such it's nothing special. These are the notification settings:

Unfortunately, the Slack channels are not public and I'm not allowed to grant access to it.

[dgtlmoon]

try 0.50.34 and let me know :)

[dgtlmoon]

Please try 0.50.33 and let me know if that solves it - lots of fixes and extra tests

[searchjaunt]

Hi,
I don't see much of a difference.
&blocks=yes is still an issue. Meanwhile I remembered why I did put it as a parameter. It was needed for iOS devices to let appear the arrows and globe icon and show the channel icon as configured in Slack for all devices. If I omit it, these icons are not shown as desired.

I also read that if would be solved if I call the webhooks directly with json in the body.
So I tried this:
posts://hooks.slack.com/services/XXX/YYY/ZZZ+content-type=application/json
and in the body
{
"summary": ":twisted_rightwards_arrows: <{{diff_url}}|Overzicht van de wijzigingen>\n:globe_with_meridians: <{{watch_url}}|Originele website>",
"diff_url": "{{diff_url}}",
"watch_url": "{{watch_url}}"
}
That doesn't seem to work either.

[dgtlmoon]

@searchjaunt try 0.50.34 and let me know :)

[searchjaunt]

Hi,
Did some testing and I think we've a working solution now. the blocks is definitely not an option but the post with json seems to work.
The previous JSON was wrong though.
It should be
{
"text": ":twisted_rightwards_arrows: <{{diff_url}}|Overzicht van de wijzigingen>\n:globe_with_meridians: <{{watch_url}}|Originele website>"
}
Not sure if ?+content-type=application/json is needed for the posts://hooks.slack.com/ URL. It seems to work without too, so I guess that changedetection sets the Content-Type automatically to application/json, no?

[dgtlmoon]

@searchjaunt Apologies, my mistake, its out now!

[searchjaunt]

First impression is that following works.

{
"text": "*{{watch_title}}*\n:twisted_rightwards_arrows: <{{diff_url}}|Overzicht van de wijzigingen>\n:globe_with_meridians: <{{watch_url}}|Originele website>"
}

The notification title is not useful anymore.

[dgtlmoon]

"The notification title is not useful anymore." what are you saying exactly? Whats the context of this comment?

[searchjaunt]

This title is ignored

One needs to put in in the json of the notification body

[dgtlmoon]

You dont say if this {{watch_title}} worked before todays update or not, i have completely no context to work with when you say "The notification title is not useful anymore."

And also if the exact same settings worked bfore todays updates or not

You need to be more verbose with me or I really just cant solve anything, sorry

[searchjaunt]

The title works when using the classic slack;// URL, meaning

When using the json body with the posts URL eg posts://hooks.slack.com/services/XXX/YYY/ZZZ, it doesn't work and the notification title is only shown when it is put in the json body. I don't know if that's normal behavior or not.