File attachments work in Copilot Studio but not after publishing

Armando Herrera 0 Reputation points
2026-08-10T04:43:52.2833333+00:00

I developed and tested my agent in the Copilot Studio Development environment. PDF, Word and Excel attachments work correctly and the agent can read and process the information.

However, after publishing the same agent to Microsoft Teams and Microsoft 365 Copilot, attached files are not being received/read by the agent. It responds as if no file was provided.

File uploads are enabled. Could you please advise why this works in Copilot Studio but not in the published channels?

Microsoft's current documentation confirms that agents can analyze uploaded files and that file uploads can be enabled for chat interactions, so this behaviour warrants investigation.

Microsoft Teams | Development
Microsoft Teams | Development

Building, integrating, or customizing apps and workflows within Microsoft Teams using developer tools and APIs

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  1. Kien 980 Reputation points Independent Advisor
    2026-08-10T07:12:54.21+00:00

    Dear @Armando Herrera,

    File input for Copilot Studio agents published to Microsoft Teams and Microsoft 365 Copilot is currently supported. Allow file input from users - Microsoft Copilot Studio | Microsoft Learn.

    Please note that the agent in Copilot Studio and the agent in Microsoft 365 Copilot are located in two separate environments. Choose between Agent Builder in Microsoft 365 Copilot and Copilot Studio to build your agent | Microsoft Learn

    I have found a similar case as your File Uploads Not Passed to Custom Engine Agent in Microsoft 365 Copilot Chat | Microsoft Community Hub and at this time, there is no roadmap date for this feature.

    To assist you in further, Microsoft’s support team will need to step in. A technical support engineer can perform a remote session to investigate the situation verify the backend configurations, and run any necessary synchronization tools to resolve the problem. If the issue requires further attention, they can refer it to a specialized team for deeper analysis.   

      Here’s what your Office 365 Global Admin should do next:       

    1. Submit a Service Request: The Global Admin should create a service request with Microsoft support to get advanced technical assistance and diagnostics. For detailed instructions on how to get support, please refer to Get support - Microsoft 365 admin. 
    2. Find Your Microsoft 365 Admin: If you’re unsure who the Global Admin is within your organization, you can find guidance on locating them here: How do I find my Microsoft 365 admin? - Microsoft Support.    
    3. Call Microsoft Support: For additional assistance, use this link to find the appropriate contact number: Global Customer Service phone numbers - Microsoft Support

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  2. Armando Herrera 0 Reputation points
    2026-08-10T05:07:02.34+00:00

    Thanks for the clarification.

    However, Microsoft’s current “Allow file input from users” documentation lists Microsoft Teams and Microsoft 365 Copilot as supported channels for file input.

    Can you please confirm whether file input for a Copilot Studio agent published to Teams and Microsoft 365 Copilot is currently supported or not?

    If it is not supported, is there a roadmap or expected date for this functionality to be available?

    This functionality is critical for our agent, as users need to upload PDF, Word and Excel documents for the agent to process.

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  3. AI answer

    2026-08-10T04:44:11.13+00:00

    This is expected in many published Copilot Studio channels today.

    The key point is that there are two different attachment experiences in the documentation:

    1. Newer attachment/file-input support exists for agents in supported surfaces such as Microsoft Teams, Microsoft 365 Copilot, web chat, and the Copilot Studio test experience.
    2. A documented publishing limitation states that, for published agents, users can't send or upload attachments to the chat, and if they do, the agent responds that it can only process text. That limitation is explicitly called out as applying to all channels, including Microsoft Teams and Direct Line, unless the message is sent to a skill that supports attachment processing.

    That explains the behavior described:

    • In the Copilot Studio test experience, attachments can work.
    • After publishing to Teams or Microsoft 365 Copilot, the same agent can behave as though no file was provided because published-channel attachment handling is limited.

    Additional channel-specific facts from the documentation:

    • File input is supported only on certain channels, including Microsoft Teams, Microsoft 365 Copilot, and the Test your agent panel.
    • File input is not supported on SharePoint, voice, or telephony channels.
    • If the agent is in a customer managed key (CMK) enabled environment, users can add files, but the agent doesn't process them.
    • For Office-style file reading, there are content limitations. For example, Word text in text boxes, shapes, SmartArt, headers, footers, or embedded objects might not be read.
    • Without code interpreter, extracted text from Office documents is limited to 30,000 characters per file and 30,000 characters total across multiple files. If exceeded, the content is discarded. PDF files are processed as the file itself, so that character limit does not apply to PDFs.

    Recommended checks:

    1. Confirm whether the published behavior matches the known limitation
      • If the agent in Teams returns a text-only style response or ignores the file, that aligns with the documented publish limitation.
    2. Verify the target channel actually supports file input
      • Supported: Teams, Microsoft 365 Copilot, custom/demo website, Facebook, Omnichannel, Test your agent.
      • Not supported: SharePoint, voice, telephony.
    3. Check whether the environment uses CMK
      • In a CMK-enabled environment, files can be attached but are not processed.
    4. Check file type and content structure
      • Supported file types include DOCX, CSV, PDF, TXT, JPG, PNG, WebP, and nonanimated GIF.
      • XLSX and PPTX are only available in experimental mode.
      • If Word files rely on text boxes, shapes, SmartArt, headers, or embedded objects, the agent may appear to miss the content.
    5. Check size and text limits
      • File input guidance lists a 15 MB individual file size restriction.
      • Without code interpreter, Office-document extracted text over the 30,000-character limit is discarded.
    6. If this must work after publishing, evaluate the documented exception
      • Attachments can be supported when the message is sent to a skill, where the skill bot supports processing attachments.

    If the scenario is specifically “works in Copilot Studio test, but not in Teams/Microsoft 365 Copilot after publish,” the most likely documented cause is the published-channel attachment limitation, not a problem with the agent logic itself.

    AI-generated content may be incorrect. Read our transparency notes for more information.

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