diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentManager.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentManager.kt
index 91672e4f..e39c6a78 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentManager.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentManager.kt
@@ -27,6 +27,7 @@ import androidx.lifecycle.MutableLiveData
 import net.taler.lib.android.assertUiThread
 import net.taler.merchantlib.CheckPaymentResponse
 import net.taler.merchantlib.MerchantApi
+import net.taler.merchantlib.MerchantConfig
 import net.taler.merchantlib.OrderHistoryEntry
 import net.taler.merchantlib.PostOrderRequest
 import net.taler.merchantpos.MainActivity.Companion.TAG
@@ -91,8 +92,8 @@ class PaymentManager(
         order: Order,
         includeProducts: Boolean = true,
     ) = scope.launch {
-        val merchantConfig = configManager.merchantConfig!!
-        val payment = Payment(order, order.summary, configManager.currency!!)
+        val merchantConfig = liveConfig() ?: return@launch
+        val payment = Payment(order, order.summary, configManager.currency ?: return@launch)
         mPayment.value = payment
         val parts = order.toOrderParts(includeProducts)
         val request =
@@ -235,7 +236,7 @@ class PaymentManager(
 
     private fun checkPayment(orderId: String) =
         scope.launch {
-            val merchantConfig = configManager.merchantConfig!!
+            val merchantConfig = liveConfig() ?: return@launch
             api.checkOrder(merchantConfig, orderId).handle(
                 { error ->
                     // don't call onNetworkError() to not cancel payment, just keep trying
@@ -369,10 +370,13 @@ class PaymentManager(
     fun cancelPayment(error: String? = null)
     {
         stopPaymentChecks()
-        val merchantConfig = configManager.merchantConfig!!
+        // Not required: cancelling has to work even when the session is the
+        // thing that ended, and then there is nobody to delete the order at.
+        val merchantConfig = configManager.merchantConfig
         mPayment.value?.let { payment ->
             // A checkout order records cash or card already taken, so it stays for resuming.
-            if (!payment.paid &&
+            if (merchantConfig != null &&
+                !payment.paid &&
                 payment.checkoutId == null)
             {
                 payment.orderId?.let { orderId ->
@@ -398,7 +402,7 @@ class PaymentManager(
             mDeleteNeedsForce.value = false
             return
         }
-        val merchantConfig = configManager.merchantConfig!!
+        val merchantConfig = liveConfig() ?: return
         val orderId = mPayment.value?.orderId ?: return
         scope.launch {
             val result = api.deleteOrder(merchantConfig, orderId)
@@ -419,7 +423,7 @@ class PaymentManager(
     @UiThread
     fun forceDeleteOrder()
     {
-        val merchantConfig = configManager.merchantConfig!!
+        val merchantConfig = liveConfig() ?: return
         val orderId = mPayment.value?.orderId ?: return
         Log.d(TAG, "Force deleting claimed order $orderId")
         scope.launch {
@@ -437,6 +441,27 @@ class PaymentManager(
         mDeleteNeedsForce.value = null
     }
 
+    /**
+     * The merchant configuration, or null once the session has ended.
+     *
+     * `ConfigManager` clears it the moment a request comes back 401, and the
+     * payment screen polls once a second -- so between two ticks of
+     * [checkTimer] the field can go from a configuration to nothing, and
+     * every `!!` on it here was a crash on the main thread waiting for a
+     * token to expire.  Where there is no session left there is also nothing
+     * useful to ask the backend, so the polling is stopped as well.
+     */
+    private fun liveConfig(): MerchantConfig?
+    {
+        val merchantConfig = configManager.merchantConfig
+        if (merchantConfig == null)
+        {
+            Log.d(TAG, "no merchant configuration left; stopping payment checks")
+            stopPaymentChecks()
+        }
+        return merchantConfig
+    }
+
     private fun stopPaymentChecks()
     {
         checkTimer.cancel()

11-08 23:25:36.451 11470 11470 E AndroidRuntime: FATAL EXCEPTION: main
11-08 23:25:36.451 11470 11470 E AndroidRuntime: Process: net.taler.merchantpos, PID: 11470
11-08 23:25:36.451 11470 11470 E AndroidRuntime: java.lang.NullPointerException
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at net.taler.merchantpos.payment.PaymentManager$checkPayment$1.invokeSuspend(PaymentManager.kt:238)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:34)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at kotlinx.coroutines.internal.DispatchedContinuationKt.resumeCancellableWith(DispatchedContinuation.kt:375)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable(Cancellable.kt:26)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at kotlinx.coroutines.CoroutineStart.invoke(CoroutineStart.kt:358)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at kotlinx.coroutines.AbstractCoroutine.start(AbstractCoroutine.kt:134)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch(Builders.common.kt:53)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at kotlinx.coroutines.BuildersKt.launch(Unknown Source:1)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch$default(Builders.common.kt:44)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at kotlinx.coroutines.BuildersKt.launch$default(Unknown Source:1)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at net.taler.merchantpos.payment.PaymentManager.checkPayment(PaymentManager.kt:237)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at net.taler.merchantpos.payment.PaymentManager.access$checkPayment(PaymentManager.kt:52)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at net.taler.merchantpos.payment.PaymentManager$checkTimer$1.onTick(PaymentManager.kt:79)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at android.os.CountDownTimer$1.handleMessage(CountDownTimer.java:145)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at android.os.Handler.dispatchMessage(Handler.java:110)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at android.os.Looper.loopOnce(Looper.java:248)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at android.os.Looper.loop(Looper.java:338)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at android.app.ActivityThread.main(ActivityThread.java:9067)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at java.lang.reflect.Method.invoke(Native Method)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:593)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:932)
11-08 23:25:36.451 11470 11470 E AndroidRuntime: 	Suppressed: kotlinx.coroutines.internal.DiagnosticCoroutineContextException: [StandaloneCoroutine{Cancelling}@8317e77, Dispatchers.Main.immediate]
11-08 23:25:36.455   690 11862 I DropBoxManagerService: add tag=data_app_crash isTagEnabled=true flags=0x2
11-08 23:25:36.460   690  2558 W ActivityTaskManager:   Force finishing activity net.taler.merchantpos/.MainActivity
11-08 23:25:36.461  1119  1183 V WindowManagerShell: Transition requested (#32): android.os.BinderProxy@42ed15e TransitionRequestInfo { type = CLOSE, triggerTask = TaskInfo{userId=0 taskId=18 effectiveUid=10216 displayId=0 isRunning=true baseIntent=Intent { flg=0x10000000 cmp=net.taler.merchantpos/.MainActivity } baseActivity=ComponentInfo{net.taler.merchantpos/net.taler.merchantpos.MainActivity} topActivity=ComponentInfo{net.taler.merchantpos/net.taler.merchantpos.MainActivity} origActivity=null realActivity=ComponentInfo{net.taler.merchantpos/net.taler.merchantpos.MainActivity} numActivities=2 lastActiveTime=2408528 supportsMultiWindow=true resizeMode=1 isResizeable=true minWidth=-1 minHeight=-1 defaultMinSize=220 token=WCT{android.window.IWindowContainerToken$Stub$Proxy@86df93f} topActivityType=1 pictureInPictureParams=null shouldDockBigOverlays=false launchIntoPipHostTaskId=-1 lastParentTaskIdBeforePip=-1 displayCutoutSafeInsets=Rect(0, 0 - 0, 0) topActivityInfo=ActivityInfo{e7e820c net.taler.merchantpos.MainActivity} launchCookies=[] positionInParent=Point(0, 0) parentTaskId=-1 isFocused=true isVisible=true isVisibleRequested=true isTopActivityNoDisplay=false isSleeping=false locusId=null displayAreaFeatureId=1 isTopActivityTransparent=false isActivityStackTransparent=false lastNonFullscreenBounds=Rect(759, 134 - 1162, 946) capturedLink=null capturedLinkTimestamp=0 requestedVisibleTypes=-9 topActivityRequestOpenInBrowserEducationTimestamp=0 appCompatTaskInfo=AppCompatTaskInfo { topActivityInSizeCompat=false eligibleForLetterboxEducation= false isLetterboxEducationEnabled= true isLetterboxDoubleTapEnabled= false eligibleForUserAspectRatioButton= false topActivityBoundsLetterboxed= false isFromLetterboxDoubleTap= false topActivityLetterboxVerticalPosition= -1 topActivityLetterboxHorizontalPosition= -1 topActivityLetterboxWidth=-1 topActivityLetterboxHeight=-1 topActivityAppBounds=Rect(0, 0 - 1920, 1080) isUserFullscreenOverrideEnabled=false isSystemFullscreenOverrideEnabled=false hasMinAspectRatioOverride=false topActivityLetterboxBounds=null cameraCompatTaskInfo=CameraCompatTaskInfo { freeformCameraCompatMode=inactive}} topActivityMainWindowFrame=null}, pipChange = null, remoteTransition = null, displayChange = null, flags = 16, debugId = 32 }
11-08 23:25:36.461   557   609 I BpBinder: onLastStrongRef automatically unlinking death recipients: 
11-08 23:25:36.464 11470 11470 I Process : Sending signal. PID: 11470 SIG: 9
11-08 23:25:36.474   557   557 I BpBinder: onLastStrongRef automatically unlinking death recipients: