ChatGPT "sandbox:/mnt/data" Link Expired or File Not Found: How to Get Your File Back
The path points to a temporary file inside a chat code sandbox. Once the surrounding environment loses that file, the old download can stop working.
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Short answer
In most cases an old link cannot be revived from the URL alone. Try the original conversation first. If the download is still broken, ask the assistant in that same conversation to recreate the file or paste the full source content. Then save the new copy immediately.
Do this first: open the original conversation and click the file control again. Do not start a separate chat expecting it to remember a temporary sandbox from another conversation.
What sandbox:/mnt/data means
A chat coding environment can mount a temporary directory for the files used in that
session. /mnt/data is a common Unix-style path for such a directory. The
text sandbox:/mnt/data/report.pdf describes a file in that workspace; it
is not the same thing as a public https:// address.
That distinction matters because a visible message can outlive the sandbox that created it. The message remains in the conversation, while the backing file may be cleaned up or replaced.
Why links expire or say "File not found"
- The temporary sandbox was recycled after the turn or after a period of inactivity.
- The file was removed or replaced while rerunning code.
- The link belongs to a different conversation or environment.
- The generated answer referred to a file that was never successfully created.
- The product changed its file-retention behaviour. UI details are as of October 2026 and can change.
Try these steps
- Return to the exact conversation and download the file again.
- Ask the assistant to recreate the file from the content already in that conversation.
- Ask it to paste the complete source text, Markdown, table or CSV as well as trying a file export.
- Save the returned text or file to your own device immediately.
- If the content is gone, rebuild it from email, project files, notes or another record.
A useful follow-up message is: “Recreate the same document from this conversation. Also return the full source as Markdown so I can save it independently of the download link.” Keep any sensitive content in the conversation where you are authorized to use it.
Rebuild the file yourself
Once you have the text or data back, making a new copy is usually faster than trying to repair the old link.
For Word and Excel formats, use your own editor while those tool pages are not yet available here. The same source text or CSV can be pasted into a new document or spreadsheet and saved with the extension you need.
Prevent it next time
- Download the file as soon as it appears in the conversation.
- Ask for the source text too, especially for important documents.
- Keep your own copy in cloud storage or version control.
- Check the file opens before closing the conversation or losing access.
- Give long documents a clear file name so you can identify the right copy later.
FAQ
Why does my ChatGPT download link say file not found?
The link may refer to a temporary file in a chat sandbox that has been cleaned up, replaced or made unavailable after the conversation ended. Reopening the same link later can therefore fail even though the message remains visible.
What is sandbox:/mnt/data?
It is a path-style reference to a file location inside a code-execution sandbox. It is not a public web address. It only makes sense while the corresponding sandbox and file are still available.
Can I recover an expired ChatGPT file?
Recovery is not guaranteed. First try the download in the original conversation. If that fails, ask the assistant to recreate the file from the same conversation or paste the source content. If the source content is gone, you need to rebuild it from other records.
How do I get ChatGPT to give me the file again?
In the original conversation, ask it to recreate the file from the content already present and provide a fresh download. Ask it to also show the full source text if the download route is unreliable, then save that text immediately.
Is sandbox:/mnt/data a real URL I can open?
No. It is typically a sandbox-internal path, not a normal public URL. Opening or editing the path outside the associated chat context is not supported, and this guide does not describe ways to access another user or another sandbox.