Status of Legacy MessageCard support in Workflows (October 28 update)

Question

Status of Legacy MessageCard support in Workflows (October 28 update)

박상혁 (Parker) 40

Hello. I am currently migrating from Office 365 Connectors to Power Automate Workflows. According to the update posted on October 28, 2025 regarding the Office 365 Connectors retirement, Microsoft stated that by December 2025, Workflows would support posting messageCard formatted payloads without needing to reformat to Adaptive Cards. However, as of today, I cannot confirm if this feature is live. Sending a legacy MessageCard JSON payload to a Workflow URL still fails, and the official documentation still explicitly states that Workflows support Adaptive Cards only. Could you confirm if the backend update has been deployed yet? We are holding off on rewriting our webhooks based on the announcement, so clarification on the timeline would be appreciated. Thank you.

Matherly, Toby 5 Reputation points

2026-02-18T18:33:35.88+00:00

The update here says Message Card support is now available as of 2/5/2026. The link provided doesn't work so where can we find instructions on how to setup the Message Card in a flow?
Teddie-D 12,845 Reputation points Microsoft External Staff Moderator

2026-02-25T05:05:03.5133333+00:00

Hi @Matherly, Toby
Here the provided link in that article Webhooks and connectors - Teams | Microsoft Learn.
For practical setup guidance, please refer to the suggested answer in the Power Platform Community thread Teams Workflows webhooks: Is MessageCard payload support live?

Matherly, Toby 5

Thank you for the link Teddy. I followed the instructions but when I actually send the message card format it fails in the workflow with the following error:

Action 'Post_card_in_a_chat_or_channel_1' failed: Microsoft.Azure.ProcessSimple.Data.Entities.Exceptions.ProcessSimpleDataException: The specified Teams flowbot adaptive card request is missing or invalid. The tracking Id is '{0}'. ---> AdaptiveCards.AdaptiveSerializationException: Property 'type' must be 'AdaptiveCard'
   at AdaptiveCards.AdaptiveCardConverter.ReadJson(JsonReader reader, Type objectType, Object existingValue, JsonSerializer serializer)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.DeserializeConvertable(JsonConverter converter, JsonReader reader, Type objectType, Object existingValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)
   at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)
   at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings)
   at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value, JsonSerializerSettings settings)
   at AdaptiveCards.AdaptiveCard.FromJson(String json)
   at Microsoft.Azure.ProcessSimple.Data.Components.AdaptiveCards.AdaptiveCardBuilder.DeserializeAdaptiveCard(String serializedAdaptiveCard, RequestIdentity requestor, CultureInfo cultureInfo, BotAdaptiveCardAtMentions atMentions) in C:\__w\1\s\src\processsimple\Roles\ProcessSimple.Data\Components\AdaptiveCards\AdaptiveCardBuilder.cs:line 930
   --- End of inner exception stack trace ---
   at Microsoft.Azure.ProcessSimple.Data.Components.AdaptiveCards.AdaptiveCardBuilder.DeserializeAdaptiveCard(String serializedAdaptiveCard, RequestIdentity requestor, CultureInfo cultureInfo, BotAdaptiveCardAtMentions atMentions) in C:\__w\1\s\src\processsimple\Roles\ProcessSimple.Data\Components\AdaptiveCards\AdaptiveCardBuilder.cs:line 934
   at Microsoft.Azure.ProcessSimple.Web.Common.Validation.BotAdaptiveCard(String card, RequestIdentity senderRequestIdentity) in C:\__w\1\s\src\processsimple\Roles\ProcessSimple.Data\Common\Validation\BotValidation.cs:line 960

Teddie-D 12,845 Reputation points Microsoft External Staff Moderator

2026-02-26T04:16:16.0233333+00:00

Hi @Matherly, Toby

AdaptiveSerializationException: Property 'type' must be 'AdaptiveCard'

This error means the JSON you’re sending to the “Post card in a chat or channel” action isn’t a valid Adaptive Card payload. The card must be wrapped correctly, and the root object must include "type": "AdaptiveCard". If "type" is missing or set to anything else, the flow fails with this exact error.
Matherly, Toby 5 Reputation points

2026-03-04T13:02:00.1833333+00:00

Teddy - What I'm sending is the Legacy MessageCard type format which I thought this was now supporting. Am I missing something here?
Teddie-D 12,845 Reputation points Microsoft External Staff Moderator

2026-03-05T06:23:41.62+00:00
Hi @Matherly, Toby

This is expected behavior, and you’re not missing a setting.

Legacy MessageCard support is available at the Teams Workflows webhook endpoint level, but not in the “Post card in a chat or channel” action.

When you create a workflow using “Send webhook to a channel”, the generated webhook URL can accept legacy MessageCard JSON directly. You can POST the MessageCard payload to that webhook URL and Teams will render it.

However, the “Post card in a chat or channel” action only accepts Adaptive Card JSON. That action validates the payload as an Adaptive Card and requires the root object to include "type": "AdaptiveCard"
Available options:

Post the MessageCard directly to the workflow webhook URL (without using the Post card action).

Convert the MessageCard to an Adaptive Card inside the flow, then use Post card in a chat or channel.

If only plain text is needed, use Post message in a chat or channel instead.
Matherly, Toby 5 Reputation points

2026-03-10T20:17:53.8666667+00:00

Teddie - The challenge for me here is the link you provided says the flow I have will work with message cards. I didn't create the flow. It was automatically created following the instructions in the other link. I have no idea how to set this up to work and I honestly can't believe microsoft isn't providing more guidance on this.
Teddie-D 12,845 Reputation points Microsoft External Staff Moderator

2026-03-11T03:36:05.8066667+00:00

Hi @Matherly, Toby
I tested the flow on my side, and it worked as expected.
I suggest starting a new thread to share more details. This will make it easier for us to request any additional information privately if needed, while also helping safeguard personal and organizational data.

Thank you for your understanding.
Matherly, Toby 5 Reputation points

2026-03-11T12:32:30.2733333+00:00

When you say start a new thread do you mean ask a new question on this forum or something else?
Teddie-D 12,845 Reputation points Microsoft External Staff Moderator

2026-03-11T23:27:54.96+00:00

Please create a new question in this forum that includes your issue, the steps you’ve already tried, your code, your flow, and the exact error message with as many details as possible. This will make it much easier for others to review and reproduce the issue. You’re welcome to tag my name if you’d like. Since this is a public platform, please remove any personal or organizational information before posting. If sensitive details are required, I or other moderators can reach out via private message first so you can share them securely.

2 answers

Your answer

Matherly, Toby 5 Reputation points

2026-02-18T18:33:35.88+00:00

The update here says Message Card support is now available as of 2/5/2026. The link provided doesn't work so where can we find instructions on how to setup the Message Card in a flow?
Teddie-D 12,845 Reputation points Microsoft External Staff Moderator

2026-02-25T05:05:03.5133333+00:00

Hi @Matherly, Toby
Here the provided link in that article Webhooks and connectors - Teams | Microsoft Learn.
For practical setup guidance, please refer to the suggested answer in the Power Platform Community thread Teams Workflows webhooks: Is MessageCard payload support live?
Teddie-D 12,845 Reputation points Microsoft External Staff Moderator

2026-02-26T04:16:16.0233333+00:00

Hi @Matherly, Toby

AdaptiveSerializationException: Property 'type' must be 'AdaptiveCard'

This error means the JSON you’re sending to the “Post card in a chat or channel” action isn’t a valid Adaptive Card payload. The card must be wrapped correctly, and the root object must include "type": "AdaptiveCard". If "type" is missing or set to anything else, the flow fails with this exact error.
Matherly, Toby 5 Reputation points

2026-03-04T13:02:00.1833333+00:00

Teddy - What I'm sending is the Legacy MessageCard type format which I thought this was now supporting. Am I missing something here?
Teddie-D 12,845 Reputation points Microsoft External Staff Moderator

2026-03-05T06:23:41.62+00:00

Hi @Matherly, Toby

This is expected behavior, and you’re not missing a setting.

Legacy MessageCard support is available at the Teams Workflows webhook endpoint level, but not in the “Post card in a chat or channel” action.

When you create a workflow using “Send webhook to a channel”, the generated webhook URL can accept legacy MessageCard JSON directly. You can POST the MessageCard payload to that webhook URL and Teams will render it.

However, the “Post card in a chat or channel” action only accepts Adaptive Card JSON. That action validates the payload as an Adaptive Card and requires the root object to include "type": "AdaptiveCard"
Available options:

Post the MessageCard directly to the workflow webhook URL (without using the Post card action).

Convert the MessageCard to an Adaptive Card inside the flow, then use Post card in a chat or channel.

If only plain text is needed, use Post message in a chat or channel instead.
Matherly, Toby 5 Reputation points

2026-03-10T20:17:53.8666667+00:00

Teddie - The challenge for me here is the link you provided says the flow I have will work with message cards. I didn't create the flow. It was automatically created following the instructions in the other link. I have no idea how to set this up to work and I honestly can't believe microsoft isn't providing more guidance on this.
Teddie-D 12,845 Reputation points Microsoft External Staff Moderator

2026-03-11T03:36:05.8066667+00:00

Hi @Matherly, Toby
I tested the flow on my side, and it worked as expected.
I suggest starting a new thread to share more details. This will make it easier for us to request any additional information privately if needed, while also helping safeguard personal and organizational data.

Thank you for your understanding.
Matherly, Toby 5 Reputation points

2026-03-11T12:32:30.2733333+00:00

When you say start a new thread do you mean ask a new question on this forum or something else?
Teddie-D 12,845 Reputation points Microsoft External Staff Moderator

2026-03-11T23:27:54.96+00:00

Please create a new question in this forum that includes your issue, the steps you’ve already tried, your code, your flow, and the exact error message with as many details as possible. This will make it much easier for others to review and reproduce the issue. You’re welcome to tag my name if you’d like. Since this is a public platform, please remove any personal or organizational information before posting. If sensitive details are required, I or other moderators can reach out via private message first so you can share them securely.

Answer 1

Hi @박상혁 (Parker)

Thank you for posting your question in the Microsoft Q&A forum.

Microsoft has shared a roadmap for moving from Office 365 Connectors to Power Automate Workflows. However, based on the most recent updates and confirmations from the community, support for the MessageCard format has not yet been made available, even though Microsoft originally targeted December 2025.

We understand this is a concern for many users, since there has been no updated ETA from Microsoft on when MessageCard handling will be enabled.

Please note that this forum is user‑to‑user support. Moderators, contributors, and external Microsoft employees here cannot make changes to product features or access back‑end systems. What we can do is share guidance based on publicly available Microsoft resources and community insights.

For the most reliable updates, we recommend following the official Retirement of Office 365 connectors within Microsoft Teams.

We know this may not be the answer you were hoping for, but until Microsoft publishes a new timeline or releases the feature, Adaptive Cards remain the only supported format for Workflows webhooks.

Thank you for your patience and understanding.

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 2

As of now, workflows in Power Automate support only Adaptive Cards and do not support the older message card format used by Office 365 Connectors. The official documentation explicitly states that workflows do not accept message card formatted payloads, and there is no indication that this feature has been deployed yet. Therefore, if you are currently experiencing failures when sending legacy MessageCard JSON payloads to a Workflow URL, it is consistent with the current limitations outlined in the documentation.

It would be advisable to proceed with rewriting your webhooks based on the existing support for Adaptive Cards, as the timeline for the legacy support update remains unclear and is not confirmed to be live at this moment.

References:

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Status of Legacy MessageCard support in Workflows (October 28 update)

2 answers

Your answer