Error on PATCH `/api/latest/fleet/software/titles/:id/package`

[BCTBB]

Fleet versions

• Discovered: v4.86.0
• Reproduced: v4.86.0

Web browser and operating system:

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💥  Actual behavior

We received a #help-p1 alert for a PATCH request that failed on /api/latest/fleet/software/titles/1662/package.

Fleet logged the following:

{"ts":"2026-06-22T19:54:19Z","level":"error","component":"http","user":"redacted@redacted.com","method":"PATCH","uri":"/api/latest/fleet/software/titles/1662/package","took":39751513529,"err":"extracting updated installer metadata: extracting metadata from installer: couldn't find bundle identifier for in-house app"}

• The software title id matches an existing entry in the software_titles table for Slack (Machine - MSI).
• The software installers table does not show a fleet_managed_app_id for the software, the value is NULL.

Unknown whether the customer was attempting to upload a version of Slack, triggering the request failure.

🛠️ Expected behavior

Improve the error message. Fleet should tell user that file type isn't supported.

🧑‍💻  Steps to reproduce

I was able to reproduce the issue on my v4.86.0 test environment. This issue can be reproduced with and without the FMA for Slack (Windows) having been added first. However, as mentioned above, it is unknown to me if the customer produced the error in the same way that I was able to reproduce it.

These steps:

• Have been confirmed to consistently lead to reproduction in multiple Fleet instances.
• Describe the workflow that led to the error, but have not yet been reproduced in multiple Fleet instances.

1. Download the official slack windows installer from the slack website.
2. Rename the file extension from .msix to .msi
3. Log into your Fleet server -> Software -> Add Software -> Custom Package
4. Upload the file that you downloaded and updated the extension to .msi
5. A banner should appear with a similar error. The error captured in the body of this issue can be found in the Fleet server logs

Couldn't add. couldn't find bundle identifier for in-house app.

🕯️ More info (optional)

N/A