Firefox .part File Won't Finish Downloading

Firefox left a .part file and the real download never completed. A .part is an in-progress download; here is how to resume it, restart it, or clear a stuck one.

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What a stuck .part file means

Firefox writes an incoming download to a file ending in .part and renames it to the real file only when the download completes. A .part that never disappears means the download stalled — the connection dropped, Firefox was closed mid-transfer, the server cut the link, or the disk filled up.

Fix it in order

Resume from the Downloads panel. Press Ctrl+Shift+Y (Windows/Linux) or Cmd+Shift+Y (Mac) to open Library → Downloads. Right-click the paused item and choose Retry / Resume.
Restart from the source. If the item shows Failed or is missing, the download link expired — reopen the original page and download again.
Remove blockers. Check for a stable connection, free disk space larger than the file, and antivirus/VPN tools that inspect downloads and can silently break the transfer.
Delete a locked leftover. If the old .part won't delete, quit Firefox completely (including background processes), then remove it from your Downloads folder.

Can you recover the partial data?

For most files, no — renaming a .part to the real extension yields a broken file, so resume or re-download instead. Progressive media (.mp4/.mp3) may play the portion that arrived if you rename a copy, but documents, archives and installers need the full transfer.

FAQ

Why won't my Firefox .part file finish?

The download was interrupted before Firefox could rename it to the real file — a dropped connection, a closed browser, a server timeout, or a full disk. Retry it from Library → Downloads, or restart from the source page.

How do I resume a stuck .part download in Firefox?

Open the Downloads library with Ctrl+Shift+Y (Cmd+Shift+Y on Mac), right-click the paused item, and choose Retry/Resume. If it failed permanently, download again from the original website.

Can I open a .part file by removing the extension?

No. A .part is only partially written, so renaming it produces a corrupt file. Some progressive video/audio may partly play, but most files must be re-downloaded.

Is it safe to delete a stuck .part file?

Yes, once the download is dead — you only lose incomplete data. Do not delete one that is still downloading. If it won't delete, quit Firefox fully first.