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()