The moment that teaches everyone this lesson is the same: you open your laptop on a plane, click the folder you need, and find a list of files that aren't there. They're placeholders. The contents are on a server you can't reach for the next nine hours.
Preventing that takes about two minutes, done in advance. Here's what to do and how offline behaviour actually works.
Mark things available offline before you leave
The setting has a different name on each service — "available offline," "always keep on this device," "pin," "make available offline" — and it does the same thing: downloads the file and keeps it, rather than evicting it later.
Do this at the folder level. Files come and go; folders persist, and folder-level pinning automatically covers new files added to them.
Then wait for it to finish. This is the step people skip. Pinning a 20GB folder and closing the laptop two minutes later gets you a partial download. Watch the sync indicator until it reports complete.
On mobile, the same applies but the interface is usually per-file or per-folder in a menu, and phones are more aggressive about reclaiming space, so verify the day you travel rather than the week before.
What to mark, for a trip
The obvious:
- Whatever you're actually going to work on
- Reference material you'll need
The easily forgotten:
- Travel documents — bookings, tickets, insurance, passport scans
- Anything you'd need in an emergency: medical information, contacts, policy numbers
- Maps, downloaded within the mapping app rather than as files
- Reading material
- Documents you'll need to send someone on arrival
The invisible dependencies:
- Fonts, linked images, and referenced assets for design files
- Templates your documents pull from
- Any file that a file you're taking depends on
That last category is the one that ruins working sessions. A design file opens and reports twelve missing links. Package or collect the project before you go, so its dependencies travel with it.
How offline editing behaves
Files in a synced folder: open, edit, and save normally. The changes sit locally, and the sync client uploads them when you reconnect. From your perspective nothing is different.
Browser-native documents need offline access explicitly enabled in the service's settings, usually per-browser, and typically only in the provider's own browser. Turn it on well in advance, because it needs to download content in the background first. Without it, the document simply won't open.
Mobile apps vary. Most let you view offline-marked files; editing support depends on the app. Assume viewing works and editing might not, unless you've tested it.
New files created offline in a synced folder upload when you reconnect. This works fine, with one caveat below about conflicts.
What reconnecting looks like
When you come back online, the client uploads everything you changed. This is usually uneventful, but three things can happen:
Conflicts. If the same file was also changed elsewhere while you were offline — by you on another device, or by a collaborator — the service can't merge them and keeps both. You'll get a (conflicted copy) file. This isn't an error; it's the system refusing to discard work. Open both, reconcile manually, delete the loser.
A large upload. If you did substantial work offline, expect a significant sync when you reconnect. Do it on Wi-Fi rather than on mobile data, and don't close the laptop mid-upload.
Deletions arriving. Anything deleted elsewhere while you were offline is deleted locally when you reconnect. If you were relying on a file that someone else removed, this is when it disappears.
The conflict risk is the reason to tell collaborators you'll be offline. Two people editing the same document offline for a week produces a merge nobody wants to do.
The offline gap nobody plans for: your phone's photos
If you're travelling and taking photos, they're sitting on your phone and nowhere else until you reach a network. That's often the most irreplaceable data you'll generate on a trip, and it's held on a single device that's more likely than usual to be lost, stolen, or dropped.
Options:
- Upload when you get Wi-Fi, deliberately, rather than assuming it happened
- Carry a small portable drive with a phone connector and copy periodically
- Copy to a laptop each evening
- If your phone supports it, a second card or an occasional copy to another device
For a long trip, do something. "It'll upload when I get home" is a bet on nothing happening to the phone for two weeks.
Mobile-specific behaviour
Phones and tablets treat offline files differently from computers:
Space reclamation is aggressive. A file you marked offline last month may have been evicted. Verify before you rely on it.
Some apps only cache what you've recently opened, rather than genuinely pinning it. Opening a file today doesn't guarantee it's there tomorrow.
Battery and background rules can interrupt downloads. Charge the phone and keep the app in the foreground while a large offline download completes.
Mobile data settings may block downloads entirely on cellular. Useful for cost control, unhelpful when you're trying to fetch a document at an airport.
The practical implication: do the offline preparation on Wi-Fi, with the device charging, and check it again shortly before you need it.
Working entirely offline for an extended period
For a genuinely long stretch — a remote trip, a location with no connectivity — treat it like packing:
Take a full local copy of what you need, not just pinned files. An external drive with the whole project on it removes any dependence on placeholder behaviour.
Take the applications and licences. Software that phones home to check a licence can fail offline. Test it in airplane mode before you go.
Take the credentials. Password managers usually work offline, but confirm yours has synced recently and that you can unlock it without a network.
Test in airplane mode, at home, before you leave. Turn off the network, open your working folder, and try to do fifteen minutes of actual work. This finds every missing piece while you can still fix it.
That last test is worth more than any checklist. It's the only way to discover the dependency you didn't know you had.
Coming back: the reconnection sequence
- Connect to Wi-Fi, not mobile data.
- Let sync finish before doing anything else. Watch the indicator.
- Check for conflicted copies — search your folder for "conflict" or "conflicted."
- Resolve them promptly, while you remember what you changed.
- Verify your work uploaded by checking one or two files in the web interface, not just the local folder.
Step five catches the case where sync silently failed on a file — usually because of a name problem or a size limit — and you'd otherwise assume it was safely stored.
The pre-travel checklist
- Marked working folders available offline, and waited for the download to complete
- Travel documents, insurance, and emergency information downloaded
- Design or project dependencies packaged with their files
- Browser offline mode enabled for native documents, and pre-loaded
- Maps downloaded in the mapping app
- Password manager synced and confirmed working offline
- Applications tested in airplane mode
- Collaborators told you'll be offline
- A plan for backing up photos taken on the trip
- Fifteen-minute airplane-mode test completed at home
Next in this series: When Cloud Storage Isn't Enough: Signs You Need a Real Backup