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Agent flow File input mapping error: “Input variable UploadFile is of incorrect type: File”

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Posted on by AM-14031710-0

I’m working in Copilot Studio and have created an agent with a topic that calls a Power Automate Agent Flow. My flow contains three input parameters:

two String inputs, and

one File input.

In the topic, I also added three corresponding output parameters of the same types.

However, when I try to map the topic variables to the flow inputs, I receive this error: “Input variable UploadFile is of incorrect type: File.”

To work around this, I attempted to manually map the File input using a formula:

{
contentBytes:
First(System.Activity.Attachments).Value,
name:
First(System.Activity.Attachments).Name
}
But when I test the agent, the flow fails to start and I get this runtime error:

Error Message: The flow 'SOC1 Vendor File Upload Flow' ('a57a9afc-df1e-f111-8341-6045bd0693d5') failed to run with response code 'BadRequest', error code: TriggerInputSchemaMismatch. Error Code: FlowActionBadRequest Conversation Id: 5bdf19fa-e48d-4ba0-89e0-3fa6b8804577 Time (UTC): 2026-03-14T17:05:01.720Z

Categories:

Calling actions from Copilot Studio

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Nivedipa-MSFT Microsoft Employee on at

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Hello AM-14031710-0,
This happens because Copilot Studio cannot pass a File variable directly to a Power Automate flow. It treats the file as a record, not a true File type.

The TriggerInputSchemaMismatch error occurs when the file record shape doesn’t match what the flow trigger expects.

The fix is to pass the file as a record with file name and file content, not as a File variable.

Make sure the file content comes from the actual file content field (not a reference or value wrapper).

After fixing the mapping, always refresh the action node, republish the agent, and start a new test conversation.

In the flow, ensure the “Create file” action uses the incoming file name and content correctly (convert to binary only if required by the connector).

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AM-14031710-0 7 on at

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The issue was caused by the File → Identify → “Include file metadata” option not being enabled in the Copilot Studio topic.

Once I selected “Include file metadata”, the File parameter mapped correctly and the flow started working as expected.

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rzaneti 4,476 Super User 2026 Season 1 on at

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Hi @AM-14031710-0,

Another possibility is to pass the System.Activity.Attachments as a value inside a JSON object and handle the logic to access the File name/content in Agent Flow/Power Automate, since a Record data type in Copilot Studio is simply a JSON. For example, you can use a formula like this:

As already mentioned, you need to convert the content inside the flow and set up the Run-only settings, if you want to use the maker's credentials to execute the SharePoint action.

You can check the implementation of a solution for this exact same use case (saving attachments from Copilot Studio to SharePoint) in this video: https://youtu.be/VPVkFyGiBmY or in this blog: https://digitalmill.net/2025/05/20/send-files-attached-by-the-user-from-microsoft-copilot-studio-to-power-automate/

Let me know if it works for you or if you need any additional help!

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