Copilot Studio Agent: DOCX/XLSX/CSV files cannot be processed via chat file upload

[Eeshkumar45]

When uploading Word (.docx) or Excel (.xlsx) files to a Copilot Studio agent using the file upload option(paperclip icon) inside the chat, the agent returns:

“I couldn’t read this file. This may be because this file type is not currently supported by Copilot Studio.”

OR

“It appears that you have not uploaded a CSV file yet. Please upload your CSV file.“

PDF files work correctly, so the issue appears to be specific to DOCX/XLSX/CSV formats.

This suggests that DOCX/XLSX/CSV are not supported for direct file-analysis, even though documentation indicates these formats are supported in other scenarios such as knowledge source ingestion.

Expected Behavior
The agent should be able to read and analyze the contents of DOCX/XLSX/CSV files
OR
If unsupported, Copilot Studio documentation should explicitly clarify that Excel and Word files cannot be processed through chat-based file upload (direct file analysis).

Actual Behavior
Uploading a .docx or .xlsx file results in the message:

“I couldn’t read this file. This may be because this file type is not currently supported by Copilot Studio.”

OR

“It appears that you have not uploaded a CSV file yet. Please upload your CSV file.“

PDF uploads are analyzed successfully.
The issue is reproducible across different tenants and environments.

Reproduction Steps

1. Open any Copilot Studio agent.
2. In the chat panel, upload a .docx or .xlsx file with some context(e.g. "List the late arrivals from this file.").
3. Observe that the agent returns the unsupported-file-type message/ no-file-uploaded message.

Screenshots

Clarification Requested

1. Are DOCX/XLSX/CSV officially supported for direct file analysis via chat upload in Copilot Studio?
2. If not supported, can Microsoft confirm this and update the documentation accordingly?
3. If this is a bug, is there a planned fix or timeline?