EllanJiang/GameFramework · error · GameFrameworkException

FSM is running, can not start again.

Error message

FSM is running, can not start again.

What it means

Fsm<T>.Start<TState>() transitions the FSM into its initial state. A state machine may only be started once; if IsRunning is already true, the guard at Fsm.cs:260 throws this exception instead of silently restarting the machine.

Solutions

1. Call Start<TState>() only once per FSM lifetime; guard subsequent calls with if (!fsm.IsRunning) fsm.Start<TState>();
2. If a restart is intended, destroy/shutdown the existing FSM (return it to ReferencePool via the FsmComponent) and recreate it before starting.
3. Move the Start call out of OnEnable into a one-time initialization path (e.g. Start() or an explicit Init method).

Example fix

// before
void OnEnable()
{
    m_Fsm.Start<IdleState>(); // throws if already running
}
// after
void OnEnable()
{
    if (m_Fsm != null && !m_Fsm.IsRunning)
    {
        m_Fsm.Start<IdleState>();
    }
}

if (m_Fsm == null || m_Fsm.IsDestroyed) { RecreateFsm(); }
if (!m_Fsm.IsRunning) { m_Fsm.Start<IdleState>(); }

bool CanStart(Fsm<MyComponent> fsm) => fsm != null && !fsm.IsRunning;

try { m_Fsm.Start<IdleState>(); }
catch (GameFrameworkException ex) { Log.Warning("FSM already started: " + ex.Message); }

When it happens

Trigger: Calling Start<TState>() twice on the same Fsm<T> instance — e.g. Start in both an init method and OnEnable, or Start called again after ChangeState/use without creating a fresh FSM.

Common situations: Unity components whose OnEnable runs multiple times (disable/enable cycles) re-calling Start; re-initializing gameplay logic without destroying and recreating the FSM via the FsmComponent; two systems each attempting to start a shared FSM.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

• FSM owner is invalid.
• FSM states is invalid.
• FSM ' ' state ' ' is already exist.
• Results is invalid.
• Already exist FSM ' '.

AI-assisted analysis of EllanJiang/GameFramework@d0c010b051 (2026-09-15). Data as JSON: /api/errors/bd77f618fa2cc6d5. Report an issue: GitHub.

Appendix: source

Thrown at GameFramework/Fsm/Fsm.cs:260

                }

                m_Datas.Clear();
            }

            m_CurrentState = null;
            m_CurrentStateTime = 0f;
            m_IsDestroyed = true;
        }

        /// <summary>
        /// 开始有限状态机。
        /// </summary>
        /// <typeparam name="TState">要开始的有限状态机状态类型。</typeparam>
        public void Start<TState>() where TState : FsmState<T>
        {
            if (IsRunning)
            {
                throw new GameFrameworkException("FSM is running, can not start again.");
            }

            FsmState<T> state = GetState<TState>();
            if (state == null)
            {
                throw new GameFrameworkException(Utility.Text.Format("FSM '{0}' can not start state '{1}' which is not exist.", new TypeNamePair(typeof(T), Name), typeof(TState).FullName));
            }

            m_CurrentStateTime = 0f;
            m_CurrentState = state;
            m_CurrentState.OnEnter(this);
        }

        /// <summary>
        /// 开始有限状态机。
        /// </summary>
        /// <param name="stateType">要开始的有限状态机状态类型。</param>
        public void Start(Type stateType)

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