What causes a web game not working offline?

The game's assets and code are fetched from the network each time, so without a connection it fails to load, and there is no offline support.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Fix a Web Game Not Working Offline

Quick answer: Cache the game's assets with a service worker, store saves locally, and handle offline gracefully so the game runs without a connection.

A web game not working offline is missing caching. A service worker fixes it. Here is how.

How to fix it

1. Cache assets with a service worker

Use a service worker to cache the game's code and assets, so they load from the cache when offline. Without caching, the game cannot load without fetching from the network.

2. Store saves locally

Keep saves in local storage (localStorage or IndexedDB) so progress works offline, syncing to the cloud when a connection returns. Saves that require the network fail offline.

3. Handle offline gracefully

Detect offline status and disable online-only features with a clear message, while letting offline play continue. A game that simply breaks offline frustrates players; one that degrades gracefully keeps working.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every HTML5 error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.

Reproduce it once with full context and the fix writes itself. The hunt is the expensive part.