diff --git a/phoss-smp-webapp/src/main/java/com/helger/phoss/smp/ui/secure/PageSecureEndpointChangeURL.java b/phoss-smp-webapp/src/main/java/com/helger/phoss/smp/ui/secure/PageSecureEndpointChangeURL.java
index fc6523f0..d39af82c 100644
--- a/phoss-smp-webapp/src/main/java/com/helger/phoss/smp/ui/secure/PageSecureEndpointChangeURL.java
+++ b/phoss-smp-webapp/src/main/java/com/helger/phoss/smp/ui/secure/PageSecureEndpointChangeURL.java
@@ -58,6 +58,7 @@
 import com.helger.phoss.smp.domain.servicegroup.ISMPServiceGroupManager;
 import com.helger.phoss.smp.domain.serviceinfo.ISMPEndpoint;
 import com.helger.phoss.smp.domain.serviceinfo.ISMPProcess;
+import com.helger.phoss.smp.domain.serviceinfo.ISMPServiceInformation;
 import com.helger.phoss.smp.domain.serviceinfo.ISMPServiceInformationManager;
 import com.helger.phoss.smp.domain.serviceinfo.SMPEndpoint;
 import com.helger.phoss.smp.ui.AbstractSMPWebPage;
@@ -119,7 +120,8 @@ public LongRunningJobResult createLongRunningJobResult ()
         // Modify all endpoints
         final MutableInt aChangedEndpoints = new MutableInt (0);
         final MutableInt aSaveErrors = new MutableInt (0);
-        final ICommonsSortedSet <String> aChangedServiceGroup = new CommonsTreeSet <> ();
+        final ICommonsList <ISMPServiceInformation> aChangedSIs = new CommonsArrayList <> ();
+        // Run in a read-lock
         aServiceInfoMgr.forEachSMPServiceInformation (aSI -> {
           if (m_aServiceGroup != null && !aSI.getServiceGroup ().equals (m_aServiceGroup))
           {
@@ -138,12 +140,20 @@ public LongRunningJobResult createLongRunningJobResult ()
               }
           if (bChanged)
           {
-            if (aServiceInfoMgr.mergeSMPServiceInformation (aSI).isFailure ())
-              aSaveErrors.inc ();
-            aChangedServiceGroup.add (aSI.getServiceGroupID ());
+            // Remember and do not merge here to avoid deadlock
+            aChangedSIs.add (aSI);
           }
         });
 
+        // Write out of read-lock
+        final ICommonsSortedSet <String> aChangedServiceGroup = new CommonsTreeSet <> ();
+        for (final var aSI : aChangedSIs)
+        {
+          if (aServiceInfoMgr.mergeSMPServiceInformation (aSI).isFailure ())
+            aSaveErrors.inc ();
+          aChangedServiceGroup.add (aSI.getServiceGroupID ());
+        }
+
         final IHCNode aRes;
         if (aChangedEndpoints.isGT0 ())
         {