Modern password managers are quiet while they work, which is exactly why sync failures feel so alarming. In Proton Pass, the difficulty is almost never lost data — your encrypted vault exists in more than one place by design — but a device that has drifted out of step: signed out without telling you, stuck offline, running an old build, or standing behind a network that refuses the connection. The fix is usually smaller than the worry.
Start by mapping the shape of the problem. Is one device behind, or is every device behind? Do the missing items exist only on the device where you created them, or did everything stop moving at once? The answers to those two questions point directly at the sections below. A single device that lags suggests a local issue; every device lagging suggests the account or the network.
Check whether the device is actually signed in
The most common sync failure is also the most polite: the app on one device has quietly signed itself out. It may still show your vault from a local cache, which makes the device look connected while nothing new is arriving. Open the app's account screen and confirm the signed-in state. If the session has expired, sign in again — and pay attention to whether the app asks for verification, because an interrupted verification flow leaves the device half-connected.
Confirm the vault is the same vault
Proton Pass can hold more than one vault, and a second vault is easy to create without noticing. If one device shows a smaller set of passwords than another, the likeliest explanation is that they are looking at different vaults rather than failing to sync the same one. Compare the vault names in each app and make sure every device is displaying the vault you expect. Switching vaults is instant and does not move any data; it only changes what you are looking at.
Rule out the offline stretch
Proton Pass keeps a local copy of your data so you can work without a connection. The trade-off is that changes made while offline wait patiently until the device reconnects — and if the connection returns only partially, or the app stays in the background, the wait can last longer than expected. Bring the app to the foreground, confirm the device is on a network that reaches Proton's servers, and give it a moment to catch up before concluding that anything is broken.
Update the client before you troubleshoot further
Sync protocols change, and older versions of an app can fall behind in ways that look like a fault. Check that the browser extension, the mobile app, and the desktop client are all on their current release. An outdated client on a single device explains a surprising number of "every device except this one" complaints. Updating is reversible and takes less time than the diagnosis that follows without it.
Inspect the network in the way
Corporate proxies, strict firewalls, and public Wi-Fi portals can interfere with the connections Proton Pass needs. A network that blocks or rewrites those connections may let the app load but prevent changes from moving. Test the same account on a different network — a mobile hotspot works well — and compare the behaviour. If sync resumes on the new network, the original network is the problem, and the right next step is to speak to its administrator rather than to reset your vault.
When a full refresh is the right answer
If the device is signed in, looking at the right vault, online, and current, a full refresh is safe and often effective. Sign out completely, clear the app's site data or cache, and sign in again. This forces the client to fetch a fresh copy of the encrypted vault instead of trusting a stale cache. It does not delete your data; the vault lives on Proton's servers and in the other signed-in clients, and a fresh sign-in simply pulls a clean copy.
What not to do when sync fails
Do not create a second account to "start fresh," do not delete the app in frustration, and do not disable two-factor authentication to speed things up. Each of those moves turns a temporary sync problem into a much larger recovery task. If a device refuses to sync after every reasonable step, record the exact error, the time, and the device model, and take those notes to official support. For more help with getting back into your account, return to the ProtonPass portal and work through the sign-in guidance there.
Keeping devices in step over the long run
Sync failures are easiest to prevent with two habits. First, keep every client updated; old versions are the single most common source of quiet divergence. Second, when you change your master password or add a new device, sign in on the others within a day or two so they refresh while the change is still fresh in your mind. Devices that are checked regularly drift less, and a device that drifts less is a device that never surprises you at the worst possible moment.