How to Fix a Unity Dedicated Server Build Crashing on a Missing Graphics Device

A Unity server that crashes the instant it launches in a Docker container is usually trying to open a graphics device on a host that has no GPU. The Dedicated Server build target removes that dependency. Here is how to configure it.

How to fix it

1. Build for the Dedicated Server subtarget

In Build Settings switch the platform to Dedicated Server and pick the Linux target. This subtarget strips the renderer, audio output, and input modules so the player never tries to create a graphics device.

2. Launch with the right flags

Run the executable with -batchmode -nographics -logFile /dev/stdout. Even on the dedicated subtarget these flags guarantee no window is created and that logs go to the container's stdout for collection.

3. Guard client-only code

Wrap any code that touches Camera, AudioListener, or UI in #if !UNITY_SERVER or runtime checks, because those subsystems are stubbed out on the server and calling them returns null or throws.

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 Unity 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.