What causes a Unity camera leaving smear trails from wrong clear flags?

The camera's Clear Flags are set to Don't Clear, so each frame draws over the previous one without clearing the buffer, smearing moving objects across the screen.

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 Unity Camera Leaving Smear Trails From Wrong Clear Flags

Quick answer: Set Clear Flags to Skybox or Solid Color for the main camera, and reserve Depth Only or Don't Clear for layered cameras that intentionally draw over another camera.

If moving objects leave trails or the screen looks like a hall of mirrors, the camera is not clearing its buffer. Fixing Clear Flags fixes it. Here is how.

How to fix it

1. Set the main camera to Skybox or Solid Color

On the primary camera set Clear Flags to Skybox (3D) or Solid Color (2D) so the framebuffer is cleared each frame and old pixels do not persist.

2. Use Depth Only for overlay cameras

A weapon or UI camera that draws on top of another should use Depth Only so it composites over the base without clearing color, but it must not be the only camera.

3. Avoid Don't Clear unless intentional

Reserve Don't Clear for deliberate trail effects; on a normal camera it produces the smearing because nothing ever wipes the previous frame.

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.

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