From f2a69620ccc9951510c7d64659abbdcc46bc83c6 Mon Sep 17 00:00:00 2001
From: andig <andi@evcc.io>
Date: Sun, 24 May 2026 10:26:36 +0200
Subject: [PATCH] OCPP: survive mid-setup disconnect on buggy chargers (#30113)
 (#30165)

---
 charger/ocpp/cp.go           | 22 ++++++++++++++++++++++
 charger/ocpp/cp_core_test.go | 26 ++++++++++++++++++++++++++
 charger/ocpp/cp_setup.go     |  7 +++++++
 charger/ocpp/helper.go       |  5 +++++
 charger/ocpp/helper_test.go  |  9 +++++++++
 5 files changed, 69 insertions(+)

diff --git a/charger/ocpp/cp.go b/charger/ocpp/cp.go
index f200eceae..90f2f2673 100644
--- a/charger/ocpp/cp.go
+++ b/charger/ocpp/cp.go
@@ -6,6 +6,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/evcc-io/evcc/api"
 	"github.com/evcc-io/evcc/util"
 	"github.com/lorenzodonini/ocpp-go/ocpp1.6/core"
 	"github.com/lorenzodonini/ocpp-go/ocpp1.6/remotetrigger"
@@ -212,6 +213,27 @@ func (cp *CP) HasConnected() <-chan struct{} {
 	return cp.connectC
 }
 
+// waitConnected blocks until the charge point is connected (i.e. a
+// BootNotification has been received after the most recent disconnect).
+// Returns immediately if already connected, otherwise waits for the next
+// BootNotification on the coalescing request channel, bounded by Timeout.
+func (cp *CP) waitConnected(ctx context.Context) error {
+	if cp.Connected() {
+		return nil
+	}
+
+	cp.log.DEBUG.Printf("charge point disconnected, waiting for reconnect")
+
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-time.After(Timeout):
+		return api.ErrTimeout
+	case <-cp.bootNotificationRequestC:
+		return nil
+	}
+}
+
 // MonitorReboot ensures the given function runs only once per CP instance.
 // Used to start the reboot monitor goroutine for multi-connector charge points.
 func (cp *CP) MonitorReboot(ctx context.Context, setup func() error) {
diff --git a/charger/ocpp/cp_core_test.go b/charger/ocpp/cp_core_test.go
index b68624ee8..c5c9e5a32 100644
--- a/charger/ocpp/cp_core_test.go
+++ b/charger/ocpp/cp_core_test.go
@@ -239,3 +239,29 @@ func TestMonitorRebootOnlyOnce(t *testing.T) {
 	require.Eventually(t, func() bool { return callCount.Load() == 1 }, time.Second, 10*time.Millisecond,
 		"setup should be called exactly once")
 }
+
+func TestWaitConnectedReturnsImmediatelyWhenConnected(t *testing.T) {
+	log := util.NewLogger("test")
+	cp := NewChargePoint(log, "test-cp")
+
+	cp.connect(true)
+	require.NoError(t, cp.waitConnected(t.Context()))
+}
+
+func TestWaitConnectedResumesOnReconnectBoot(t *testing.T) {
+	log := util.NewLogger("test")
+	cp := NewChargePoint(log, "test-cp")
+
+	// not connected, simulates the CP having dropped mid-setup
+	require.False(t, cp.Connected())
+
+	// schedule a reconnect's BootNotification after a short delay
+	go func() {
+		time.Sleep(20 * time.Millisecond)
+		_, _ = cp.OnBootNotification(&core.BootNotificationRequest{
+			ChargePointModel: "TestModel",
+		})
+	}()
+
+	require.NoError(t, cp.waitConnected(t.Context()))
+}
diff --git a/charger/ocpp/cp_setup.go b/charger/ocpp/cp_setup.go
index b5d4bae8c..b2d246adf 100644
--- a/charger/ocpp/cp_setup.go
+++ b/charger/ocpp/cp_setup.go
@@ -18,6 +18,13 @@ func (cp *CP) Setup(ctx context.Context, meterValues string, meterInterval time.
 		cp.log.DEBUG.Printf("failed configuring availability: %v", err)
 	}
 
+	// Some chargers (e.g. EN+/EVSEDO FW 1.1.805, issue #30113) hang on ChangeAvailability
+	// and drop the WebSocket. Without this, every subsequent request fails with
+	// "no client exists" and aborts charger creation fatally.
+	if err := cp.waitConnected(ctx); err != nil {
+		return err
+	}
+
 	// auto configuration
 	desiredMeasurands := "Power.Active.Import,Energy.Active.Import.Register,Current.Import,Voltage,Current.Offered,Power.Offered,SoC"
 
diff --git a/charger/ocpp/helper.go b/charger/ocpp/helper.go
index 894965fad..13834f042 100644
--- a/charger/ocpp/helper.go
+++ b/charger/ocpp/helper.go
@@ -31,6 +31,11 @@ func wait(err error, rc chan error) error {
 		if oe, ok := errors.AsType[*ocpp.Error](err); ok && oe.Code == ocppj.GenericError {
 			err = api.ErrTimeout
 		}
+	} else if strings.Contains(err.Error(), "no client") {
+		// The ocpp-go dispatcher returns "cannot send request ..., no client ... exists"
+		// when the CP disconnected before the request could be queued. Treat as transient
+		// timeout so callers can react to a reconnect instead of aborting setup fatally.
+		err = api.ErrTimeout
 	}
 	return err
 }
diff --git a/charger/ocpp/helper_test.go b/charger/ocpp/helper_test.go
index 6a7acf587..65d274afb 100644
--- a/charger/ocpp/helper_test.go
+++ b/charger/ocpp/helper_test.go
@@ -1,13 +1,22 @@
 package ocpp
 
 import (
+	"errors"
 	"testing"
 	"time"
 
+	"github.com/evcc-io/evcc/api"
 	"github.com/lorenzodonini/ocpp-go/ocpp1.6/types"
 	"github.com/stretchr/testify/assert"
 )
 
+func TestWaitMapsNoClientToTimeout(t *testing.T) {
+	// dispatcher returns this verbatim when the CP disconnected before the request could be queued
+	err := errors.New("cannot send request 4711, no client ABC123 exists")
+	got := wait(err, nil)
+	assert.ErrorIs(t, got, api.ErrTimeout)
+}
+
 func TestSortByAge(t *testing.T) {
 	assert.Equal(t, []types.MeterValue{
 		{Timestamp: nil},