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 the “GetControlID mismatch” Warning in a Unity Custom Editor

Q: What causes the GetControlID mismatch warning in a Unity custom editor?

Your OnInspectorGUI emits a different number of EditorGUI controls between the layout and repaint passes, usually because a field is drawn inside an if that depends on event state.

Quick answer: Draw the same set of controls on every IMGUI pass and toggle them with disabled groups or visibility, instead of skipping calls conditionally so the control-ID stream stays consistent.

IMGUI assigns control IDs in call order across two passes per frame. If your inspector draws fewer controls during repaint than layout, the IDs no longer line up and Unity warns about a mismatch.

How to fix it

1. Never branch the control count

Avoid wrapping EditorGUILayout calls in conditions that change between the Layout and Repaint events. Draw every field unconditionally so the control-ID sequence is identical on both passes.

2. Disable instead of hide

When a field should be inactive, wrap it in EditorGUI.BeginDisabledGroup(cond) / EndDisabledGroup() rather than skipping the draw call. The control still exists, so IDs stay aligned.

3. Use FocusType.Passive for manual IDs

If you call GUIUtility.GetControlID yourself, pass a stable hint and the same FocusType every frame so the requested ID does not drift between passes.

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.

The bug you can't reproduce isn't gone — it's just invisible until you capture it from the player's device.