Fix: Unity Async Scene Load Progress Stuck at 90 Percent

Loading bar fills smoothly to 90% and freezes. Players think the game crashed. Unity holds at 0.9 by design until you allow activation.

The Symptom

op.progress climbs to 0.9 and stops. Scene activates anyway after a hitch. Or with allowSceneActivation = false, hangs at 0.9 forever.

The Fix

public class SceneLoader : MonoBehaviour
{
    public Image bar;

    public IEnumerator LoadAsync(string scene)
    {
        var op = SceneManager.LoadSceneAsync(scene);
        op.allowSceneActivation = false;

        while (op.progress < 0.9f)
        {
            bar.fillAmount = op.progress / 0.9f;
            yield return null;
        }

        // Smoothly fill to 100% before activation
        var t = 0f;
        while (t < 0.4f)
        {
            t += Time.deltaTime;
            bar.fillAmount = Mathf.Lerp(bar.fillAmount, 1f, t);
            yield return null;
        }
        bar.fillAmount = 1f;

        op.allowSceneActivation = true;
    }
}

Bar fills 0→1 over the actual load duration plus a small finish lerp. Player sees full bar before activation.

Activation Hitch

Activation calls Awake on every scene root. Heavy Awake methods cause a freeze frame. Optimize Awake or split work into a coroutine triggered after activation.

Verifying

Add a print of op.progress per frame. Should climb to 0.9, hold, then activate. With activation: scene swaps. Bar reaches 100% in your UI before the swap.

“Scale to 0.9. Block activation. Smooth lerp to 100. Flip the switch.”

Related Issues

For Addressables async, see handle leak. For async unobserved exception, see async exceptions.

Scale progress. Block activation. Reveal at 100.