What causes a Unity sub-state machine that plays no state?

The sub-state machine's internal Entry node has no transition to a default state, so when control enters the sub-machine there is no state to play.

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 Animator Sub-State Machine Not Entering Because It Has No Entry Transition

Quick answer: Open the sub-state machine and connect its Entry node to the intended default state, or right-click that state and choose Set as Layer Default State.

Grouping locomotion into a sub-state machine keeps the graph tidy, but if entering it produces a blank pose, the Entry node has nowhere to go. Here is how to wire it.

How to fix it

1. Connect the Entry node

Double-click into the sub-state machine and drag a transition from the Entry node to the state that should play first. Mecanim needs this to know the default destination.

2. Set a default state

Right-click the intended starting state and choose Set as Layer Default State. The default shows orange and is what Entry resolves to when no condition routes elsewhere.

3. Handle the exit too

Add a transition to the Exit node so control can leave the sub-state machine. A sub-machine with no exit can trap the Animator inside it.

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.