Fix common file-sharing problems on phones and computers
Step-by-step troubleshooting for QR camera permissions, slow WebRTC transfers, offline senders, expired rooms, mobile downloads and browser errors.
The QR opens a page but will not scan in the browser
On mobile browsers, camera access normally requires a secure HTTPS context or your development address. In-app camera scanning requires a secure HTTPS connection.
You can often use the phone camera app to scan a printed QR and open its URL. If the QR still fails, copy the invite URL manually. Avoid putting private room links in search-indexable pages.
The room shows the sender offline
A file announced in a sharing room is not automatically copied into permanent cloud storage. In direct mode, the sender usually has to keep the browser tab active. If the sender closes the tab, changes network, or the operating system suspends the app, the connection may end.
The online count is based on active connections, and a disconnect can take several seconds to detect. A new tab or a different browser profile can represent a separate session.
The 2 GB movie is transferring too slowly
Peer-to-peer transfers are limited by the sender upload rate, recipient download rate, congestion, disk performance and network connection type. Speed estimates are not guaranteed throughput tests. At a sustained 2 MB/s, even 2 GiB takes over 17 minutes, not counting connection setup or retries.
Use a longer room duration for large files so the receiver has time to begin. Avoid locking the phone during transfer. Prefer a browser supporting streaming to disk. Confirm that the sender has sufficient upload bandwidth and that neither device is on a restricted corporate or carrier network.
The WebRTC connection cannot start
Direct peer connections can fail when both users are behind restrictive NATs or firewalls. STUN helps peers discover possible paths, but it cannot solve every network scenario. A TURN relay can solve some failures when a relay is configured and within its quota.
MallowShare does not promise universal free relaying. For a simple diagnosis, try a small file between the same devices, then another network. A successful local transfer does not prove worldwide compatibility.
Downloads, ZIPs or file conversions fail
Check free disk space and whether your browser supports streaming saves. Building a ZIP in memory is intentionally size-limited; large files should be downloaded as individual originals. For a text PDF to Word conversion, the PDF must contain extractable text or the OCR library must be installed; scanned pages can be inaccurate.
If an older version keeps appearing, close previous server windows, open the versioned new local address, then reload. Service-worker cached assets can survive an update; a new app version should use a new cache key.
Share a private support report instead of the file itself
The Receiver Ready Check in MallowShare can explain supported browser features, secure-context status and storage estimates, without uploading or opening the selected files. You can download a plain-text report for troubleshooting. Never paste a room password or full invite token into a public support forum.