How to Fix Unity Input.GetButtonDown Missed When Read in FixedUpdate

If your jump sometimes does nothing, you are reading a one-frame input in FixedUpdate and missing it. Reading in Update and buffering fixes it. Here is how.

How to fix it

1. Read one-shot input in Update

Call Input.GetButtonDown("Jump") in Update and set jumpQueued = true. GetButtonDown is only valid for one Update frame and FixedUpdate may skip it.

2. Consume the flag in FixedUpdate

In FixedUpdate apply the jump when jumpQueued is true, then reset it. This bridges the input frame into the physics step deterministically.

3. Keep continuous reads where they belong

Use GetButton (held) or axis reads directly in FixedUpdate; only the edge-triggered GetButtonDown/GetButtonUp need buffering.

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.