Few things are as irritating as an upload dying at 80 percent. You have already waited twenty minutes, the progress bar stops, and something unhelpful appears about the transfer failing.
The good news is that failed transfers almost always come down to a short list of causes, and most of them are avoidable on the second attempt once you know which one hit you. This guide works through the likely culprits in the order they actually occur, and explains what can be salvaged versus what has to start over.
One thing to be clear about first: this is about transfers that failed while sending. If your files uploaded fine and the link has since expired, that is a different situation - expired shares are permanently deleted and cannot be recovered by anyone, including us. See what happens to files after you share them.
Key takeaways
- Most failures are connection drops, not anything wrong with your file
- Chunked uploads can often resume where they stopped rather than restarting
- Sleep settings and background tabs kill more uploads than bad internet does
- If a file is near the size ceiling, splitting it is more reliable than retrying
Step 1: Work Out What Actually Failed
The fix depends entirely on where it broke.
It failed instantly, before any progress. Almost certainly a size or file-count limit, or the file never got selected properly. Check the numbers before blaming the connection.
It climbed then stopped partway. A connection interruption, a sleeping device, or a browser tab that got suspended. This is the most common case by far.
It reached 100% then errored. The upload finished but the finalising step failed. Often worth simply refreshing and checking - sometimes the share exists and you just never saw the confirmation.
It works on one network and not another. Corporate or school networks frequently block or throttle large uploads. Try a different connection.
Step 2: The Common Causes
Your connection dropped
Wi-Fi is not as stable as it feels. Moving between rooms, a router hiccup, a phone switching from Wi-Fi to mobile data mid-upload - any of these interrupt the stream.
The switch from Wi-Fi to cellular is a particularly sneaky one on phones. If Wi-Fi gets weak, the phone silently hands over to mobile data, and the upload session breaks even though you never lost "internet."
Fix: stay put during a big upload, use ethernet if you have it, and on a phone consider turning mobile data off so it cannot switch mid-transfer.
The device went to sleep
Laptops sleep on a timer, phones lock their screens, and both can suspend network activity when they do. A 2 GB upload that needs fifteen minutes will not survive a five-minute sleep setting.
Fix: change the power setting before starting anything large, or just keep the device awake. On a phone, keep the screen on and the browser in the foreground.
The browser tab lost focus
Mobile browsers in particular suspend background tabs to save battery. Switching to another app during an upload can pause or kill it.
Fix: leave the tab open and in front. On a phone, do not switch apps until it finishes.
You hit a limit
Every service has ceilings. Here, a single share holds up to 100 files and 3 GB in total. Going over either stops the upload immediately rather than partway.
There are also daily caps in place to prevent abuse, so a very heavy day of uploading can hit a wall that has nothing to do with the current file. Signed in, a further ceiling applies: a free account holds 50 GB of live shares at once, and an upload that would push you past it is refused with a message saying how much room is left. Deleting a finished share or letting one expire frees the space immediately.
Fix: check the file count and total size. If you are over, split the batch into two shares - see how to split a large file into parts.
The network blocks large uploads
Workplace, school, hotel, and some public networks apply limits or inspect traffic in ways that break long uploads. This is why a transfer can fail repeatedly at the office and work first time at home.
Fix: try a different network, or tether to your phone briefly.
Step 3: What Can Be Resumed
Large uploads here are sent in pieces rather than as one enormous request. Each piece is confirmed as it arrives, which means an interrupted transfer has often already banked most of its progress.
In practice that means retrying is frequently much faster than the first attempt, because the parts that already made it do not need sending again. If a transfer fails near the end, retry before assuming you have to start from scratch.
What cannot be resumed is a share that was never completed and then abandoned for a long time. Incomplete uploads are cleaned up rather than left sitting around, so come back to a failed transfer promptly rather than tomorrow.
Step 4: Make the Retry Succeed
Before starting again, stack the odds:
Zip lots of small files into one archive. A hundred separate files means a hundred chances to fail. One archive means one. It is also faster. See how to compress files before sharing.
Plug in. Ethernet where possible, mains power always. Both remove a category of failure.
Close the streaming. Uploads compete with everything else on your connection. A 4K stream in the next room genuinely slows you down.
Start with a test. If a big transfer keeps failing, send a 10 MB file first. If that fails too, the problem is the network, not the size.
Check your actual upload speed. Home connections upload far slower than they download. A "100 Mbps" line often uploads at 10. Knowing the real number tells you whether twenty minutes is normal or a symptom.
When It Still Will Not Work
If you have tried a different network, a smaller test file, and a fresh browser, and it still fails, the file itself may be the problem - a corrupted archive or a file still being written to by another program will fail consistently.
Try copying the file to a new location first, then uploading the copy. If your video editor or backup tool still has the file open, close it before uploading.
Preventing It Next Time
The single biggest improvement is starting large uploads when you are not about to move, sleep, or switch networks. Most failed transfers are not technical faults - they are a laptop lid closing.
For anything genuinely large, consider whether you need to send the whole thing at once. Two 1.5 GB shares are more robust than one 3 GB share, and the recipient barely notices the difference.
The Short Version
Check whether you hit a limit, then assume a connection or sleep interruption. Retry promptly, since completed parts often carry over. Zip small files together, plug in, and stay on one network until it finishes.
And remember the distinction that matters: a failed upload can be retried, but an expired share is gone for good.
Try your transfer again, or read how to send large files online.