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Earlier versions of Webhooks reject embed-only payloads from Discord and Slack compatible apps with error 400, newest first.

Current version | Edited by Rex
Changes
Add webook under discord, slack, or generic webhook into Zerobyte. Then test.Removed: ### Environment (optional)Removed: Removed: _No response_Removed: Removed: ### Logs or screenshots (optional)Removed: Removed: _No response_Removed: Removed: ### ChecksRemoved: Removed: - ☑ I searched for existing issues and didn't find a duplicate.Removed:
Show

Webhooks reject embed-only payloads from Discord and Slack compatible apps with error 400

Summary

When attempting to use webhooks via many popular self hosted apps, I've found that embed only may not be supported on the webhook. For example, within seer sending a test payload I receive the following error in the apps logs: Using the discord webhook integration: 
2026-02-23T16:08:46.438Z [debug][Notifications]: Sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}
2026-02-23T16:08:46.559Z [error][Notifications]: Error sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"INVALID_FORM_BODY","message":"Invalid form body.","errors":[{"path":"message_data","message":"Invalid message data.","code":"INVALID_MESSAGE_DATA"}]}}
Using the slack webhook integration: 
2026-02-23T16:10:39.644Z [debug][Notifications]: Sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}
2026-02-23T16:10:39.796Z [error][Notifications]: Error sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"CANNOT_SEND_EMPTY_MESSAGE","message":"You can't send an empty message."}}
Zerobyte results in a generic 400 error: 
16:15:12 error Failed to send notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request

16:15:12 error ...../api/v1/notifications/destinations/6/test: Failed *** send test notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request
Pretty sure Zerobyte uses Shoutrrr for sending out webhooks in most of its processes. Odd that the Unraid System notification works fine when using the discord notification - it shows up as an embed only which is intended. I originally thought that may have been the problem.

Steps to reproduce

Add webook under discord, slack, or generic webhook into Seer. Then test. Add webook under discord, slack, or generic webhook into Zerobyte. Then test.
Edited by Rex
Changes
Removed: Error 400 with certain webhook replacementsAdded: Webhooks reject embed-only payloads from Discord and Slack compatible apps with error 400### Summary
Show

Webhooks reject embed-only payloads from Discord and Slack compatible apps with error 400

Summary

When attempting to use webhooks via many popular self hosted apps, I've found that embed only may not be supported on the webhook. For example, within seer sending a test payload I receive the following error in the apps logs: Using the discord webhook integration: 
2026-02-23T16:08:46.438Z [debug][Notifications]: Sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}
2026-02-23T16:08:46.559Z [error][Notifications]: Error sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"INVALID_FORM_BODY","message":"Invalid form body.","errors":[{"path":"message_data","message":"Invalid message data.","code":"INVALID_MESSAGE_DATA"}]}}
Using the slack webhook integration: 
2026-02-23T16:10:39.644Z [debug][Notifications]: Sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}
2026-02-23T16:10:39.796Z [error][Notifications]: Error sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"CANNOT_SEND_EMPTY_MESSAGE","message":"You can't send an empty message."}}
Zerobyte results in a generic 400 error: 
16:15:12 error Failed to send notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request

16:15:12 error ...../api/v1/notifications/destinations/6/test: Failed *** send test notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request
Pretty sure Zerobyte uses Shoutrrr for sending out webhooks in most of its processes. Odd that the Unraid System notification works fine when using the discord notification - it shows up as an embed only which is intended. I originally thought that may have been the problem.

Steps to reproduce

Add webook under discord, slack, or generic webhook into Seer. Then test. Add webook under discord, slack, or generic webhook into Zerobyte. Then test.

Environment (optional)

No response

Logs or screenshots (optional)

No response

Checks

  • ☑ I searched for existing issues and didn't find a duplicate.
Edited by Rex
Changes
16:15:12 error ...../api/v1/notifications/destinations/6/test: Failed *** send test notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad RequestAdded: ```Pretty sure Zerobyte uses Shoutrrr for sending out webhooks in most of its processes.
Show

Error 400 with certain webhook replacements

Summary

When attempting to use webhooks via many popular self hosted apps, I've found that embed only may not be supported on the webhook. For example, within seer sending a test payload I receive the following error in the apps logs: Using the discord webhook integration: 
2026-02-23T16:08:46.438Z [debug][Notifications]: Sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}
2026-02-23T16:08:46.559Z [error][Notifications]: Error sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"INVALID_FORM_BODY","message":"Invalid form body.","errors":[{"path":"message_data","message":"Invalid message data.","code":"INVALID_MESSAGE_DATA"}]}}
Using the slack webhook integration: 
2026-02-23T16:10:39.644Z [debug][Notifications]: Sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}
2026-02-23T16:10:39.796Z [error][Notifications]: Error sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"CANNOT_SEND_EMPTY_MESSAGE","message":"You can't send an empty message."}}
Zerobyte results in a generic 400 error: 
16:15:12 error Failed to send notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request

16:15:12 error ...../api/v1/notifications/destinations/6/test: Failed *** send test notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request
Pretty sure Zerobyte uses Shoutrrr for sending out webhooks in most of its processes. Odd that the Unraid System notification works fine when using the discord notification - it shows up as an embed only which is intended. I originally thought that may have been the problem.

Steps to reproduce

Add webook under discord, slack, or generic webhook into Seer. Then test. Add webook under discord, slack, or generic webhook into Zerobyte. Then test.

Environment (optional)

No response

Logs or screenshots (optional)

No response

Checks

  • ☑ I searched for existing issues and didn't find a duplicate.
Edited by Rex
Changes
2026-02-23T16:10:39.644Z [debug][Notifications]: Sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}2026-02-23T16:10:39.796Z [error][Notifications]: Error sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"CANNOT_SEND_EMPTY_MESSAGE","message":"You can't send an empty message."}}Added: ```Zerobyte results in a generic 400 error:Added: ```16:15:12 error Failed to send notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request
Show

Error 400 with certain webhook replacements

Summary

When attempting to use webhooks via many popular self hosted apps, I've found that embed only may not be supported on the webhook. For example, within seer sending a test payload I receive the following error in the apps logs: Using the discord webhook integration: 
2026-02-23T16:08:46.438Z [debug][Notifications]: Sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}
2026-02-23T16:08:46.559Z [error][Notifications]: Error sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"INVALID_FORM_BODY","message":"Invalid form body.","errors":[{"path":"message_data","message":"Invalid message data.","code":"INVALID_MESSAGE_DATA"}]}}
Using the slack webhook integration: 
2026-02-23T16:10:39.644Z [debug][Notifications]: Sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}
2026-02-23T16:10:39.796Z [error][Notifications]: Error sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"CANNOT_SEND_EMPTY_MESSAGE","message":"You can't send an empty message."}}
Zerobyte results in a generic 400 error: ``` 16:15:12 error Failed to send notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request 16:15:12 error ...../api/v1/notifications/destinations/6/test: Failed *** send test notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request Pretty sure Zerobyte uses Shoutrrr for sending out webhooks in most of its processes. Odd that the Unraid System notification works fine when using the discord notification - it shows up as an embed only which is intended. I originally thought that may have been the problem.

Steps to reproduce

Add webook under discord, slack, or generic webhook into Seer. Then test. Add webook under discord, slack, or generic webhook into Zerobyte. Then test.

Environment (optional)

No response

Logs or screenshots (optional)

No response

Checks

  • ☑ I searched for existing issues and didn't find a duplicate.
Edited by Rex
Changes
2026-02-23T16:08:46.438Z [debug][Notifications]: Sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}2026-02-23T16:08:46.559Z [error][Notifications]: Error sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"INVALID_FORM_BODY","message":"Invalid form body.","errors":[{"path":"message_data","message":"Invalid message data.","code":"INVALID_MESSAGE_DATA"}]}}Added: ```Using the slack webhook integration:Added: ```2026-02-23T16:10:39.644Z [debug][Notifications]: Sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}2026-02-23T16:10:39.796Z [error][Notifications]: Error sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"CANNOT_SEND_EMPTY_MESSAGE","message":"You can't send an empty message."}}
Show

Error 400 with certain webhook replacements

Summary

When attempting to use webhooks via many popular self hosted apps, I've found that embed only may not be supported on the webhook. For example, within seer sending a test payload I receive the following error in the apps logs: Using the discord webhook integration: 
2026-02-23T16:08:46.438Z [debug][Notifications]: Sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}
2026-02-23T16:08:46.559Z [error][Notifications]: Error sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"INVALID_FORM_BODY","message":"Invalid form body.","errors":[{"path":"message_data","message":"Invalid message data.","code":"INVALID_MESSAGE_DATA"}]}}
Using the slack webhook integration: ``` 2026-02-23T16:10:39.644Z [debug][Notifications]: Sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"} 2026-02-23T16:10:39.796Z [error][Notifications]: Error sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"CANNOT_SEND_EMPTY_MESSAGE","message":"You can't send an empty message."}} Zerobyte results in a generic 400 error: 16:15:12 error Failed to send notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request 16:15:12 error ...../api/v1/notifications/destinations/6/test: Failed *** send test notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request Pretty sure Zerobyte uses Shoutrrr for sending out webhooks in most of its processes. Odd that the Unraid System notification works fine when using the discord notification - it shows up as an embed only which is intended. I originally thought that may have been the problem.

Steps to reproduce

Add webook under discord, slack, or generic webhook into Seer. Then test. Add webook under discord, slack, or generic webhook into Zerobyte. Then test.

Environment (optional)

No response

Logs or screenshots (optional)

No response

Checks

  • ☑ I searched for existing issues and didn't find a duplicate.
Edited by Rex
Changes
Using the discord webhook integration:Added: Added: ```2026-02-23T16:08:46.438Z [debug][Notifications]: Sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"}2026-02-23T16:08:46.559Z [error][Notifications]: Error sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"INVALID_FORM_BODY","message":"Invalid form body.","errors":[{"path":"message_data","message":"Invalid message data.","code":"INVALID_MESSAGE_DATA"}]}}
Show

Error 400 with certain webhook replacements

Summary

When attempting to use webhooks via many popular self hosted apps, I've found that embed only may not be supported on the webhook. For example, within seer sending a test payload I receive the following error in the apps logs: Using the discord webhook integration: ``` 2026-02-23T16:08:46.438Z [debug][Notifications]: Sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"} 2026-02-23T16:08:46.559Z [error][Notifications]: Error sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"INVALID_FORM_BODY","message":"Invalid form body.","errors":[{"path":"message_data","message":"Invalid message data.","code":"INVALID_MESSAGE_DATA"}]}} Using the slack webhook integration: 2026-02-23T16:10:39.644Z [debug][Notifications]: Sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"} 2026-02-23T16:10:39.796Z [error][Notifications]: Error sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"CANNOT_SEND_EMPTY_MESSAGE","message":"You can't send an empty message."}} Zerobyte results in a generic 400 error: 16:15:12 error Failed to send notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request 16:15:12 error ...../api/v1/notifications/destinations/6/test: Failed *** send test notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request Pretty sure Zerobyte uses Shoutrrr for sending out webhooks in most of its processes. Odd that the Unraid System notification works fine when using the discord notification - it shows up as an embed only which is intended. I originally thought that may have been the problem.

Steps to reproduce

Add webook under discord, slack, or generic webhook into Seer. Then test. Add webook under discord, slack, or generic webhook into Zerobyte. Then test.

Environment (optional)

No response

Logs or screenshots (optional)

No response

Checks

  • ☑ I searched for existing issues and didn't find a duplicate.
Original by Rex
Show

Error 400 with certain webhook replacements

Summary

When attempting to use webhooks via many popular self hosted apps, I've found that embed only may not be supported on the webhook. For example, within seer sending a test payload I receive the following error in the apps logs: Using the discord webhook integration: 2026-02-23T16:08:46.438Z [debug][Notifications]: Sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"} 2026-02-23T16:08:46.559Z [error][Notifications]: Error sending Discord notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"INVALID_FORM_BODY","message":"Invalid form body.","errors":[{"path":"message_data","message":"Invalid message data.","code":"INVALID_MESSAGE_DATA"}]}} Using the slack webhook integration: 2026-02-23T16:10:39.644Z [debug][Notifications]: Sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification"} 2026-02-23T16:10:39.796Z [error][Notifications]: Error sending Slack notification {"type":"TEST_NOTIFICATION","subject":"Test Notification","errorMessage":"Request failed with status code 400","response":{"code":"CANNOT_SEND_EMPTY_MESSAGE","message":"You can't send an empty message."}} Zerobyte results in a generic 400 error: 16:15:12 error Failed to send notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request 16:15:12 error ...../api/v1/notifications/destinations/6/test: Failed *** send test notification: failed to send notification to generic webhook: server returned unexpected response status code: 400 Bad Request Pretty sure Zerobyte uses Shoutrrr for sending out webhooks in most of its processes. Odd that the Unraid System notification works fine when using the discord notification - it shows up as an embed only which is intended. I originally thought that may have been the problem.

Steps to reproduce

Add webook under discord, slack, or generic webhook into Seer. Then test. Add webook under discord, slack, or generic webhook into Zerobyte. Then test.

Environment (optional)

No response

Logs or screenshots (optional)

No response

Checks

  • ☑ I searched for existing issues and didn't find a duplicate.