Excel Copilot WebView2 crashes when rendering download links - Bug

Question

&nbsp;Environment: Excel for Microsoft 365 (Desktop)Windows 10/11 - Enterprise accountIssue:Excel Copilot's WebView2 panel goes completely black/blank when attempting to render download links for files generated in the Python sandbox.Steps to Reproduce:Open Excel with CopilotAsk Copilot to perform any task that generates a download link (e.g., "create a test file and give me a download link")&nbsp;WebView2 panel turns black immediatelyWhat I've Tried:Clearing WebView2 cache at: %LOCALAPPDATA%\Microsoft\Office\16.0\Wef\webview2\Copilot works normally after cache clear UNTIL a download link is requestedIssue is reproducible every timeWorkaround:Asking Copilot to write results directly to sheets instead of generating download files works fine.This started after an Excel crash during a Copilot session.

ferg1 · Answer

Further update with screenshots:Excel Copilot generates a sandbox download-file reference, but the Excel Copilot UI displays the file reference as plain text rather than presenting an actionable download link/file control.&nbsp;&nbsp;Issue:Copilot in Excel does not render generated sandbox download files as actionable links/file controls.Reproduction:Ask Copilot in Excel to create a small test text file and provide the download. Copilot reports successful creation and displays Download sandbox-link-test.txt, but the displayed text is not an actionable download control. Expanding “Reasoned in 1 step” only displays the reasoning details.Control:Other WebView/browser links are displayed and usable.Troubleshooting:Windows/Excel environment rebooted and test repeated; behaviour remained the same.Evidence:Two screenshots showing collapsed and expanded reasoning states.&nbsp;&nbsp;┌─────────────────────────────────────────────────────────────────┐│ CLOUD SANDBOX&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; │&nbsp;│ ┌─────────────┐&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;│&nbsp;&nbsp;│ │ Python code&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;│ → Creates file in sandbox&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ││ └─────────────┘&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;│ └────────────────────────────┬────────────────────────────────────┘&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;│&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ▼┌─────────────────────────────────────────────────────────────────┐│ EXCEL/OFFICE BROKER (Local)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ││ - Receives file from sandbox&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;││ - Renders download link in WebView2&nbsp; &nbsp;← FAILURE POINT&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ││ - Saves to Documents\Copilot\Created\ ← NOT AVAILABLE&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; │└─────────────────────────────────────────────────────────────────┘Generate trivial file&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ↓Copilot says file created&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ↓Filename/reference appears&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ↓No actionable download control&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ↓Reboot Windows&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ↓Repeat&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ↓Same resultUPDATE - Further Debugging:Confirmed via testing:Normal HTTPS links render correctly in WebView2 (not a general WebView2 failure)Can manually write to Documents\Copilot\Created\ via PowerShell (folder permissions OK)Hover states and JavaScript work normally in the panelConclusion: The failure is isolated to the **sandbox download broker pathway** - the component that transfers files from Copilot's cloud sandbox to local storage and renders the download link.Suspected cause: A policy change (Defender Controlled Folder Access, Purview DLP, WebView2 GPO, or Office Connected Experiences policy) may be blocking the brokered download, and instead of showing an error, WebView2 crashes/blacks out.IT investigation requested for: - WebView2-specific policies (separate from Edge browser GPOs) - Defender Controlled Folder Access events - ASR rules affecting EXCEL.EXE or msedgewebview2.exe - Windows Event Viewer logs for crash events&nbsp;&nbsp;&nbsp;

ferg1 · Answer

Excel Agent / Copilot UI becomes stuck in “Still working on it”. Subsequent prompts may receive contradictory responses claiming the session is active, while response text renders incorrectly one word per line. Generated sandbox artefacts also appear as plain text rather than downloadable file controls. Issue persists after reboot. Installed WebView2 Evergreen Runtime is 155.0.4283.62.

Went to try and "revive" a stalled Excel agent (in browser), by starting a new conversation with an Excel agent (in browser, not in Excel).

Plain text: Definitely something wrong with Excel agent...as still unresponsive

Please can you revive the agent in this conversation as it seems to have fallen asleep and is unresponsive to last message: Excel Sandbox Download Links Suppressed

Excel said:

Excel

I’m

active

now

.

No

stalled

background

agent

is

visible

to

revive

,

and

no

workbook

exists

in

this

session

.

Please

resend

the

last

Excel

request

or

upload

the

source

file

,

and

I

’ll

recreate

the

workbook

here

.

I’m active now. No stalled background agent is visible to revive, and no workbook exists in this session. Please resend the last Excel request or upload the source file, and I’ll recreate the workbook here.

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Excel Copilot WebView2 crashes when rendering download links - Bug

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