M365 Copilot-created file placed at unreachable URL: sandbox:/mnt/data

Maria Mingallon 175

We are encountering a recurring issue where Microsoft 365 Copilot creates files that are saved to an unreachable URL: sandbox:/mnt/data. This behavior has been observed in multiple contexts:

When using M365 Copilot chat
When interacting with Microsoft Copilot agents via browser app or Teams
When working within the Notebook experience

This issue prevents users from accessing the generated files, disrupting workflows and causing confusion.

A similar topic was previously raised in the Microsoft Answers forum (https://answers.microsoft.com/en-us/msoffice/forum/all/m365-copilot-created-file-placed-at-unreachable/54cedad9-20fe-4b67-a9e3-11ea0bf1dd60?page=1&messageId=b68870a6-c171-4bc3-a09b-6ebe2533be08), but it has not been successfully addressed by Microsoft so far.

We are raising this again in hopes of receiving a definitive explanation and resolution. Specifically, we would like to understand:

Why are files being saved to sandbox:/mnt/data?
Is this expected behavior or a bug?
What steps can be taken to retrieve or redirect these files to an accessible location?

Thank you for your support.

Gee777 Disciple 70 Reputation points

2025-07-08T22:26:02.5766667+00:00

I am also having the same issue, somebody please help!
Jimbob1986 0 Reputation points

2025-07-15T13:39:48.9566667+00:00

any update on this?
QuickBrownFox 41 Reputation points

2025-07-17T22:17:17.09+00:00

I can confirm this happens when chatting with Copilot M365 in a Notebook context, just as @Harrie Boonen wrote. In a "normal" M365 Copilot chat conversation, documents are generated with working hyperlinks and downloadable.
Would like to hear from Microsoft about this issue...
QuickBrownFox 41 Reputation points

2025-07-17T22:28:42.1566667+00:00

Update: Microsoft has acknowledged the issue and is working on it:
https://admin.cloud.microsoft/?#/servicehealth/:/alerts/CP1116386
Kluge, Christine 0 Reputation points

2025-07-24T18:27:57.53+00:00

same issue here
Mike Conrad 0 Reputation points

2025-07-26T00:14:04.88+00:00

An update was due today. This is now impacting all of my chats and custom agents.
Neal Williams 5 Reputation points

2025-07-28T14:53:01.81+00:00

Same issue here
Rebecca H Meller 0 Reputation points

2025-07-30T00:56:46.36+00:00

same issue here
James Gill 30 Reputation points

2025-08-11T19:37:59.9366667+00:00

Opened a ticket with M$ suppport a week or so ago for exactly this issue and they linked me to this answer in their support ticket. So as of 8/11/2025, this is an ongoing issue with no permanent fix. Go figure, Microsoft is perfectly willing to let us buy licenses for and spend $51/mo on a broken product. Criminal stuff here...
Thain, Jane 0 Reputation points

2025-08-27T07:40:04.1266667+00:00

I am encountering the same issue with agents I create, but one agent that is in development mode is creating word documents and putting them in downloads without issue. Its telling me it is using python to get around the issue? But will not advise how I can do the same with my other agents. Are there detailed instructions for how to get agents to create accessible downloads? I'm creating agents via Teams and Co-pilot studio but I'm no Power automate expert and the instructions co-pilot gives are incorrect or outdated.
Digbijoy Sarker 0 Reputation points

2025-09-05T01:05:50.1933333+00:00

I am also having the same issue. Unable to download the file from sandbox storage
Colin Millar 0 Reputation points

2025-09-08T03:55:09.6933333+00:00

Same same several months later in researcher
Jason Melz 0 Reputation points

2025-09-08T19:19:27.8533333+00:00

Issue still happening with me
Mohamad AlKhatib 0 Reputation points

2025-09-18T07:45:47.4866667+00:00

i have same issue, any updates?
Krajnik, Andrew 0 Reputation points

2025-09-23T21:41:45.0066667+00:00

Same issue here. Copilot has completely lost the ability to generate files. All links show a non-clickable link to a "sandbox:/mnt/data/" url.
Hamza Qamar 0 Reputation points

2025-10-07T17:29:32.56+00:00

It has been solved now. Enable to code interpreter in the custom agent and it will give downloadable links.
coffeebreak-5773 5 Reputation points

2025-10-08T17:30:21.02+00:00

Oct 8 2025 - this is back after gap.

Copilot goes into a loop if you ask how to download from or access the sandbox location. This was about a script which copilot earlier showed directly into the chat but now it puts it in sandbox location. This is maddening.
If I ask to generate the script directly in the chat it says "I am sorry the script was not available in the sandbox location" and fails to generate the script.
Scott Hay 40 Reputation points

2025-11-06T13:42:48.49+00:00

I’ve been experiencing this issue for several months: when I try to generate a file with Microsoft 365 Copilot in the Windows 11 app, it only produces internal sandbox:/ links instead of usable download links. These links are invalid and cannot be opened.

This occurs specifically when using a Copilot Lite agent to create Word or PDF output files. The lack of a working download option forces me to copy and paste content manually into Word, which defeats the purpose of file generation.

Could this be addressed so that Copilot consistently provides proper downloadable file cards or links, rather than inaccessible sandbox references?

6 answers

Pierre Baret 0 Reputation points

2025-12-11T16:01:51.6+00:00

I faced the same issue discussing with chat about a coding project, at some point I asked to generate the project after all the back and forth discussion and he generated it under "/mnt/data/image_reviewer" which does not exist on my windows laptop obviously.

My work around was the following prompt: "can you zip the generated repo so I can download it"

it worked like a charm.
Please sign in to rate this answer.

0 comments No comments
Sign in to comment

Use comments to ask for clarification, additional information, or improvements to the question.

Share via

M365 Copilot-created file placed at unreachable URL: sandbox:/mnt/data

6 answers

Your answer