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NovaVMS Manual

Export produces an empty file

Symptom

You export from the Events page and the resulting CSV has only the header row and no data — or you click Download on the event player and the saved MP4 will not play.

Downloads folder with the exported file showing "0 bytes" size

Likely causes

  1. Your filter on the Events page returned zero rows. A CSV export of an empty filter produces a header-only file.
  2. The event’s clip status is failed or snapshot only. The source video is missing — there is nothing to download.
  3. Object storage permissions are broken. The cloud server’s presigned URL fails — the browser saves an empty or unplayable file.

Fix

If the CSV is empty (header only)

Narrow your diagnosis before re-exporting:

  1. Clear the filter and confirm the Events page actually has rows.
  2. If the page has rows, re-apply filters one at a time. A common case is an over-narrow date range (e.g. the date picker collapsed to a single hour with no events).
  3. If the filter is correct and rows are present in the UI but the CSV is still empty, report a ticket — this is a known-bad state.

If the MP4 download is unplayable

  1. Open the event you tried to download. Play it inline first — if the player cannot play the clip either, the source clip is unavailable.
  2. Check the event’s Clip status on the event detail page. If it shows failed or snapshot only, the source video is missing — the download is not supported for snapshot-only events in v1.
  3. Object storage permissions: ask your admin to confirm the cloud server can read the clip from GCS / S3 / MinIO. Presigned URL generation logs (search the cloud slog output for the event ID) will show the error if any.

Verify

  1. For CSV: open the file — it has the header row plus at least one data row that matches what you saw in the UI.
  2. For MP4: the file plays in a standard player (VLC, QuickTime, Chrome’s built-in file:// preview).

If none of this worked

Collect the event ID (visible in the URL on the event detail page) and the approximate time of the export. Open a ticket at support.novalien.com.

See also: