What causes a web game blocked by Content Security Policy?

A Content Security Policy on the page blocks inline scripts, eval, WebAssembly, or external resources the game uses, so the game fails to load or run with CSP errors in the console.

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 Blocked by Content Security Policy

Quick answer: Adjust the CSP to allow what the game needs (wasm-eval, script sources), avoid inline scripts and eval where blocked, and serve assets from allowed origins.

A web game blocked by CSP is a policy too strict for the game. Adjusting it fixes it. Here is how.

How to fix it

1. Allow what the game needs

The CSP must permit the script sources, WebAssembly (wasm-unsafe-eval or wasm-eval), and connect/asset origins the game uses. Adjust the policy to allow these, since a strict default blocks the game.

2. Avoid inline scripts and eval

If the CSP blocks inline scripts or eval and you cannot change it, move scripts to external files and avoid eval-based code generation. Many CSP failures are inline scripts the policy disallows.

3. Serve assets from allowed origins

Load assets from origins the CSP's connect-src and img-src allow. An asset from a disallowed origin is blocked. Either host assets on an allowed origin or add the origin to the policy.

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.

Ship the fix, watch the signature disappear from the next build. That's how you know it's really gone.