A download link is not working: five reasons, in order

Someone sends you a link, you click it, and you get an error instead of a file. Almost always the cause is one of five things, and four of them you can resolve yourself in under a minute.

Work down this list in order.

1. The link expired

The most common reason by a distance. Transfer links are meant to stop working — that is the feature, not a fault. The sender chose a window when they sent it: a day, a week, a month.

When a link expires here, the files are deleted, not hidden. There is no version of the file sitting behind the error waiting to be released, and nobody at either end can bring it back. The fix is to ask the sender to send it again, which takes them seconds.

If you are the sender and this keeps happening, the lesson is not necessarily to use longer expiries — it is to send the link when the recipient is ready to act on it.

2. The sender revoked it

Senders can kill a link deliberately, usually because they sent the wrong version, sent it to the wrong person, or the work is finished. It looks identical to expiry from where you are standing.

Same fix: ask. If they revoked it on purpose you will find out quickly, and if they did it by accident they will be glad you asked.

3. The link got broken in transit

This is the one that looks the most mysterious and is the most fixable.

Long URLs get damaged by the things that carry them:

• Line wrapping. A mail client breaks the URL across two lines and only the first half becomes clickable. Copy the whole thing, including whatever is on the next line, and paste it into the address bar.
• Chat apps truncating. Some shorten a long link visually and mangle it on copy.
• Autocorrect. Phones capitalise the first letter, and links are case-sensitive.
• A missing fragment. This is the big one for encrypted transfers — see below.

Ask for the link again in a plain-text message, or ask the sender to paste it a second time.

4. The key is missing from the link

If the transfer is encrypted, the decryption key travels in the part of the URL after the #. That is deliberate: browsers never send the fragment to a server, so the key reaches you without ever reaching us.

The side effect is that anything which strips the fragment breaks the link. Some link shorteners, some corporate link-scanning systems, and a few chat apps drop everything after the hash. What you are left with resolves to a page asking for a key you do not have.

Two ways out. Ask the sender to resend the full link somewhere that will not touch it, or ask them for the key separately — the download page has a field for it, and typing it in works exactly the same way.

If the sender chose to pass the key by hand in the first place, check your other messages: it will be in one of them, four groups of four characters.

5. Something on your network is blocking it

Less common, easy to test. Corporate networks and school networks sometimes block file-transfer domains outright, or a scanner sits between you and the download and times out on anything large.

The tell is that the page will not load at all rather than loading and showing an error. Try the link on a phone using mobile data rather than the office wifi. If it works there, the problem is the network and the answer is your IT team.

If the download starts and then fails

A different problem, and worth separating. If the page works and the file begins downloading but stops partway or arrives unusable, the transfer is being truncated rather than blocked.

• Check the free space on your disk. A large file failing near the end is often simply nowhere to put it.
• Retry on a stable connection, preferably wired.
• If it fails at the same point every time, tell the sender — that points at the stored file rather than at your connection, and they should send it again.

On an encrypted transfer, a truncated download usually fails to open rather than producing a corrupt file, because each chunk is authenticated. An error is more useful than a file that looks fine until someone tries to use it. More on that in when a downloaded file will not open.

What to tell the sender

If you have to go back to them, these three things save a round trip:

• What you see — an expiry message, a key prompt, or nothing loading at all.
• Whether the link was clicked from an email, a chat app, or pasted by hand.
• Whether you have tried a different network.

Related: how long a download link should last explains why links expire on purpose, and end-to-end encryption explained covers the fragment and the key.