PairOnce

TROUBLESHOOTING · INTERRUPTED TRANSFER

File transfer interrupted or stuck? How to continue it

Keep both pages open and let the same two devices connect again: the sending page shows Interrupted · continues when the connection is back and carries on by itself.

A file over 16 MB continues from where it stopped when the receiver is Chrome or Edge on a computer or an Android phone, Firefox on a computer, or Safari on iOS 26 or later, and the devices reconnect within 30 minutes; a smaller file is quick to send again in full.

If it keeps stopping, look at the usual causes first: a phone screen that locks, a network that drops, or a page that was closed or reloaded.

Step by step

  1. Keep both pages open. The part that has arrived waits in the receiving page. If that page is closed or reloaded, the transfer cannot continue and the file is sent again from the start; the leftover is cleared the next time PairOnce opens. If the sending page is closed, choose the file again.
  2. Wake the phone and keep the screen on. A locked or sleeping phone can pause the page and drop the connection in the middle of a file. PairOnce asks the browser to keep the screen on during a transfer where the browser allows it; for large files also turn off auto-lock.
  3. Connect the two devices again. If they do not reconnect by themselves, open PairOnce on both and tap Connect next to the other device in your list. The sending page then shows the file as continuing, and the receiving page asks only for the rest.
  4. Check how the devices are connected. On the same Wi-Fi the file goes straight across with no monthly limit. When a network does not allow that, an encrypted relay carries 200 MB a month per device (5 GB with PairOnce Pro). A VPN or an office network can be the reason the direct route is blocked.
  5. If it starts again from the start, let it. After 30 minutes, or once a fourth cut-off file pushes an older one out, the next attempt sends the whole file again. Keep the original until the other device has saved it.

What continues and what is sent again

A file over 16 MB goes straight to the receiving browser’s storage on that device. If the connection drops, the part already written is kept for 30 minutes, for up to 3 cut-off files, and the same paired device continues the same chosen file from that point. This works when the receiver is Chrome or Edge on a computer or an Android phone, Firefox on a computer, or Safari on iOS 26 or later.

A file of 16 MB or less, and a file on a receiver that holds files in page memory, is sent again in full when the connection returns; the sending page then says it sends again when the connection is back. Such a receiver takes files up to 50 MB.

Why transfers stop in the first place

The usual reasons are a phone that went to sleep, a Wi-Fi or mobile-data connection that dropped, a VPN or office network that blocks the direct route, and a page that was closed or reloaded on either side. Both pages stay open and online for the whole transfer.

When a transfer is slow rather than stopped, check the connection: the same Wi-Fi is the fastest route, and a relay is the way through when a network blocks the direct one.

From the command line

With the PairOnce command-line tool, a large file that was cut off continues when it is sent again, on the receiving side of `npx paironce receive`.

Limits, and when this is not the right tool

  • A file can be up to 2 GB over a direct connection when the receiving browser saves straight to disk (Chrome or Edge on a computer or Android, Firefox on a computer, Safari on iOS 26 or later). Other browsers take up to 50 MB per file and hold 100 MB of received files at a time.
  • Files over 2 GB need PairOnce Pro on one of the two devices. Then a file can be up to 10 GB, received the same way, and the relay carries 5 GB a month.
  • When the two devices cannot reach each other directly, an encrypted relay carries the data. Each device can send and receive 200 MB a month that way, counted together; a direct connection has no monthly limit.
  • Both pages must stay open until everything has arrived: keep the phone’s screen on and the browser in front.
  • PairOnce moves things between two devices that are open at the same time. It is not cloud storage: nothing waits on a server for later.

Other ways to do it

  • Split the file. Cut a big video or archive into smaller parts, or send a few files at a time, so a cut-off costs less.
  • A cloud drive. Uploads first and downloads later, so it can be finished from either device; it needs an account, and the file waits on a server until it is downloaded.
  • A USB cable or a drive. Needs no network, if you have the right cable and the computer can read the device.
  • Your system’s own sharing. AirDrop between Apple devices or Quick Share between Android and Windows cover those pairs of devices.

Common questions

Does PairOnce resume a transfer after a dropped connection?

Yes for a file over 16 MB when the receiver is Chrome or Edge on a computer or an Android phone, Firefox on a computer, or Safari on iOS 26 or later: the receiving page keeps what arrived for 30 minutes and the same device continues from there. A smaller file is sent again in full.

How long is the half-received file kept?

30 minutes, for up to 3 cut-off files at a time, and only while the receiving page stays open. A page that was closed or reloaded cannot continue it.

Is my phone’s screen lock the problem?

Often. A locked phone can pause the page and cut the connection. Keep the screen on and the page in front until the file is saved.

Why is the transfer so slow?

Check the connection first: the same Wi-Fi is the fastest route. When a network blocks the direct route, PairOnce uses an encrypted relay, which can be slower on networks that block UDP. Turning off a VPN can help.

How big can a file be?

Up to 2 GB per file when the receiving browser is Chrome or Edge (computer or Android), Firefox on a computer, or Safari on iOS 26 or later, and 10 GB with PairOnce Pro on one of the two devices. Other receivers take files up to 50 MB.