I think it depends on whether you work in a notebook environment or the conversation environment in coPilot M365. The former creates links to downloadable sites, but they don't work, whereas the latter does, apparently.
M365 Copilot-created file placed at unreachable URL: sandbox:/mnt/data
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.
Microsoft Copilot | Microsoft 365 Copilot | Development
3 answers
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Lemus, Ricardo 0 Reputation points
2025-07-31T20:11:48.3366667+00:00 Exactly the same output/behavior - I did request the agent to generate a downloadable link, but no luck either! keep sending the sandbox:/mnt/data
Any workaround that had worked so far? Thanks
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Eugene Petzer 0 Reputation points
2025-08-29T10:56:00.1266667+00:00 So MS said they fixed this, but obviously not!
Some users may incorrectly receive suggestions by Microsoft Copilot (Microsoft 365) to generate a file download link
Issue ID: CP1116386
Affected services: Microsoft Copilot (Microsoft 365)
Status: Service restored
Issue type: Advisory
Start time: 11 Jul 2025, 01:00 BST
End time: 4 Aug 2025, 11:00 BST
User impact
Users may have incorrectly received suggestions by Copilot to generate a file download link.
More info
This issue occurred for declarative agents, SharePoint agents, or Copilot notebooks when code interpreter was disabled and users were returned a broken link. When Copilot generated a file, the link provided pointed users to "sandbox:/mnt/data/FILE_NAME" which wasn't an accessible environment.
This behavior was encountered when using either a declarative agent or a notebook.
Users hosted outside of the Government Cloud environment that were using a Copilot declarative agent could have enabled code interpreter to alleviate impact while we continued to investigate this incident.
Scope of impact
Some users may have incorrectly received suggestions by Copilot to generate a file that resulted in a broken download link while code interpreter was disabled.
Root cause
A recent update to help improve Copilot capabilities produced a code issue that was resulting in unexpected suggestions by Copilot.
Next steps
- We're reviewing our update testing and validation procedures to identify opportunities to improve impact detection and better prevent similar future occurrences.
Current status
4 Aug 2025, 17:17 BST
We've completed the deployment of our fix to remediate the issue and received confirmation from a subset of users that impact was successfully resolved. Any users seeing persisting impact are advised to refresh their browser session to ensure they're on the latest build to experience remediation.
This is the final update for the event.
History of updates
1 Aug 2025, 16:48 BST
We've completed validation of the fix and initiated deployment in the affected environments. As deployment progresses, some users may begin to see impact alleviation. Based on current estimates, we expect deployment to complete and the issue to be fully resolved by our next scheduled update.
28 Jul 2025, 17:32 BST
The internal validations of the fix to address the affected declarative agents and Copilot notebooks are now progressing as expected, and we're observing success from our testing. We expect to begin deploying the fix to the affected environment by the end of this week, and we'll provide a timeline for deployment to the affected environment as one becomes available.
25 Jul 2025, 17:19 BST
Due to an issue impacting our internal testing environment, our internal validations of the fix were delayed. We're now proceeding with our initial validations to confirm the efficacy of our fix, and anticipate we'll have a timeline for deployment to the affected environment with our next scheduled update.
23 Jul 2025, 18:17 BST
We're completing our internal validations and tests for our fix to ensure it addresses the affected declarative agents and Copilot notebooks without introducing any unexpected problems to the service. We're expecting the validations to be completed and a timeline for our fix deployment to be available by our next scheduled update.
22 Jul 2025, 16:23 BST
Our internal fix testing and validations are ongoing as we work to ensure it fixes the issue for both declarative agents and impacted notebooks.
21 Jul 2025, 16:38 BST
Our additional root cause analysis has isolated an update to the Copilot service that’s producing a code issue which is resulting in the unexpected suggestions by Copilot. We're developing a fix that will address the code problem and remediate the impact. We're expecting that our internal fix testing and validations will have completed and that an estimated timeline for our fix deployment will be available by our next scheduled update.
17 Jul 2025, 23:28 BST
We've determined that code interpreter must be enabled to generate a file download link and that Copilot is attempting to perform this function when it isn't enabled by default. Based on our improved understanding of this event, we’ve updated the Title, User impact, and Scope of impact fields of our communication. To remediate impact, we're identifying ways of to correct Copilots behavior so that it informs users that this function isn't available if code interpreter isn't enabled.
16 Jul 2025, 23:32 BST
We’re investigating the code interpreter configuration to determine our next troubleshooting steps and what actions we can take to resolve this issue. While we investigate, we’ve validated that users of a Copilot declarative agent can enable code interpreter to alleviate impact while we continue to investigate this incident.
16 Jul 2025, 20:56 BST
We're continuing our analysis of the code interpreter configuration to better understand its relation to the impact before we can progress with the development of a mitigation strategy.
16 Jul 2025, 18:45 BST
Our investigation has led us to suspect the impact may be related to a code interpreter configuration, and we're working to confirm this suspicion before determining our next steps towards mitigation.
16 Jul 2025, 17:31 BST
We're reviewing the HTTP Archive (HAR) logs provided by some affected users to help determine our next troubleshooting steps
16 Jul 2025, 17:00 BST
We're investigating a potential issue with Copilot and checking for impact to your organization. We'll provide an update within 30 minutes.