diff --git a/BTCPayServer.Plugins.Payjoin/Plugin.cs b/BTCPayServer.Plugins.Payjoin/Plugin.cs
index 36a0714..0592b6b 100644
--- a/BTCPayServer.Plugins.Payjoin/Plugin.cs
+++ b/BTCPayServer.Plugins.Payjoin/Plugin.cs
@@ -60,6 +60,7 @@ public override void Execute(IServiceCollection applicationBuilder)
             provider.GetRequiredService<BTCPayNetworkProvider>(),
             provider.GetRequiredService<PayjoinReceiverSessionStore>(),
             provider.GetRequiredService<PayjoinMailroomManager>(),
+            provider.GetRequiredService<PayjoinOhttpKeysProvider>(),
             provider.GetRequiredService<PayjoinAvailabilityService>(),
             provider.GetRequiredService<PayjoinSessionBuildLock>(),
             provider.GetRequiredService<IPayjoinAccountingBridgeService>(),
diff --git a/BTCPayServer.Plugins.Payjoin/Services/PayjoinOhttpKeysProvider.cs b/BTCPayServer.Plugins.Payjoin/Services/PayjoinOhttpKeysProvider.cs
index b639476..46fc4f4 100644
--- a/BTCPayServer.Plugins.Payjoin/Services/PayjoinOhttpKeysProvider.cs
+++ b/BTCPayServer.Plugins.Payjoin/Services/PayjoinOhttpKeysProvider.cs
@@ -13,8 +13,10 @@ namespace BTCPayServer.Plugins.Payjoin.Services;
 
 public sealed class PayjoinOhttpKeysProvider
 {
-    // TODO: Consider making this configurable if 12 hours is not a good duration for caching OHTTP keys.
-    private static readonly TimeSpan OhttpKeysCacheDuration = TimeSpan.FromHours(12);
+    // Directory OHTTP keys can rotate; a shorter lifetime bounds how long stale keys are served, and
+    // Invalidate lets a failed session build drop them immediately instead of waiting out the window.
+    // TODO: Consider making this configurable if one hour is not a good duration for caching OHTTP keys.
+    private static readonly TimeSpan OhttpKeysCacheDuration = TimeSpan.FromHours(1);
 
     // TODO: Consider making this configurable if 10 seconds is not a good timeout for fetching OHTTP keys.
     private static readonly TimeSpan OhttpKeysFetchTimeout = TimeSpan.FromSeconds(10);
@@ -121,6 +123,13 @@ internal async Task<PayjoinOhttpKeysFetchResult> FetchKeysAsync(
         }
     }
 
+    // Stale directory OHTTP keys are one way session construction fails; dropping the cached
+    // keys costs at most one refetch and lets the next attempt start from fresh material.
+    internal void Invalidate(string storeId, SystemUri ohttpRelayUrl, string directoryUrl)
+    {
+        _memoryCache.Remove(CreateCacheKey(storeId, ohttpRelayUrl, directoryUrl));
+    }
+
     internal static string CreateCacheKey(string storeId, SystemUri ohttpRelayUrl, string directoryUrl)
     {
         return $"PayjoinOhttpKeys_{storeId}_{ohttpRelayUrl.AbsoluteUri}_{directoryUrl}";
diff --git a/BTCPayServer.Plugins.Payjoin/Services/PayjoinUriSessionService.cs b/BTCPayServer.Plugins.Payjoin/Services/PayjoinUriSessionService.cs
index a1ff1a3..f55164e 100644
--- a/BTCPayServer.Plugins.Payjoin/Services/PayjoinUriSessionService.cs
+++ b/BTCPayServer.Plugins.Payjoin/Services/PayjoinUriSessionService.cs
@@ -35,6 +35,7 @@ public sealed class PayjoinUriSessionService
     private readonly BTCPayNetworkProvider _networkProvider;
     private readonly PayjoinReceiverSessionStore _receiverSessionStore;
     private readonly PayjoinMailroomManager _mailroomManager;
+    private readonly PayjoinOhttpKeysProvider _ohttpKeysProvider;
     private readonly PayjoinAvailabilityService _availabilityService;
     private readonly PayjoinSessionBuildLock _sessionBuildLock;
     private readonly IPayjoinAccountingBridgeService _accountingBridgeService;
@@ -44,6 +45,7 @@ internal PayjoinUriSessionService(
         BTCPayNetworkProvider networkProvider,
         PayjoinReceiverSessionStore receiverSessionStore,
         PayjoinMailroomManager mailroomManager,
+        PayjoinOhttpKeysProvider ohttpKeysProvider,
         PayjoinAvailabilityService availabilityService,
         PayjoinSessionBuildLock sessionBuildLock,
         IPayjoinAccountingBridgeService accountingBridgeService,
@@ -52,6 +54,7 @@ internal PayjoinUriSessionService(
         _networkProvider = networkProvider;
         _receiverSessionStore = receiverSessionStore;
         _mailroomManager = mailroomManager;
+        _ohttpKeysProvider = ohttpKeysProvider;
         _availabilityService = availabilityService;
         _sessionBuildLock = sessionBuildLock;
         _accountingBridgeService = accountingBridgeService;
@@ -129,19 +132,31 @@ public async Task<string> BuildAsync(
 
             if (session is null)
             {
-                var selectedRelay = await _mailroomManager.SelectBootstrapRouteAsync(
+                var bootstrapRoute = await _mailroomManager.SelectBootstrapRouteAsync(
                     storeSettings,
                     storeId,
                     invoiceId,
                     cancellationToken).ConfigureAwait(false);
 
-                if (selectedRelay is null)
+                if (bootstrapRoute is null)
                 {
                     return LogUnexpectedFallbackAndReturnBip21(bip21, invoiceId, "OHTTP keys are unavailable from all configured relays");
                 }
 
                 var bootstrapPersister = new CapturingReceiverSessionPersister();
-                InitializeSession(destination, due, selectedRelay.DirectoryUrl.AbsoluteUri, selectedRelay.OhttpKeys, monitoringExpiresAt, bootstrapPersister);
+                try
+                {
+                    InitializeSession(destination, due, bootstrapRoute.DirectoryUrl.AbsoluteUri, bootstrapRoute.OhttpKeys, monitoringExpiresAt, bootstrapPersister);
+                }
+                catch (UniffiException)
+                {
+                    // Stale directory OHTTP keys are one way session construction fails; dropping the
+                    // cached keys costs at most one refetch and lets the next attempt start from fresh
+                    // material. Replayed sessions never reach here, so their failures keep the cache.
+                    _ohttpKeysProvider.Invalidate(storeId, bootstrapRoute.RelayUrl, bootstrapRoute.DirectoryUrl.AbsoluteUri);
+                    throw;
+                }
+
                 session = _receiverSessionStore.CreateSession(
                     invoiceId,
                     destination,