diff --git a/dotnet/IEC61850forCSharp/IEC61850ServerAPI.cs b/dotnet/IEC61850forCSharp/IEC61850ServerAPI.cs
index 7aa303ba..5126b30e 100644
--- a/dotnet/IEC61850forCSharp/IEC61850ServerAPI.cs
+++ b/dotnet/IEC61850forCSharp/IEC61850ServerAPI.cs
@@ -1529,6 +1529,8 @@ namespace IEC61850
 
                         entryId = octetStringVal.getOctetString();
 
+                        octetStringVal.Dispose();
+
                         return entryId;
                     }
                     else
diff --git a/src/iec61850/inc/iec61850_server.h b/src/iec61850/inc/iec61850_server.h
index 48c79533..670f5c85 100644
--- a/src/iec61850/inc/iec61850_server.h
+++ b/src/iec61850/inc/iec61850_server.h
@@ -1549,7 +1549,7 @@ typedef enum {
     RCB_EVENT_GI,            /* << GI report triggered */
     RCB_EVENT_PURGEBUF,      /* << Purge buffer procedure executed */
     RCB_EVENT_OVERFLOW,      /* << Report buffer overflow */
-    RCB_EVENT_REPORT_CREATED /* << a new report was created and inserted into the buffer */
+    RCB_EVENT_REPORT_CREATED /* << A new report was created and inserted into the buffer */
 } IedServer_RCBEventType;
 
 /**
diff --git a/src/iec61850/inc_private/mms_mapping_internal.h b/src/iec61850/inc_private/mms_mapping_internal.h
index 79c9e793..3e896495 100644
--- a/src/iec61850/inc_private/mms_mapping_internal.h
+++ b/src/iec61850/inc_private/mms_mapping_internal.h
@@ -323,7 +323,9 @@ struct sMmsMapping {
 #endif /* (CONFIG_IEC61850_SERVICE_TRACKING == 1) */
 
     /* flag indicates if data model is locked --> prevents reports to be sent */
+
     bool isModelLocked;
+    Semaphore isModelLockedMutex;
 
     IedServer iedServer;
 
diff --git a/src/iec61850/server/impl/ied_server.c b/src/iec61850/server/impl/ied_server.c
index 6534fb7b..9d750ddf 100644
--- a/src/iec61850/server/impl/ied_server.c
+++ b/src/iec61850/server/impl/ied_server.c
@@ -811,9 +811,13 @@ IedServer_stopThreadless(IedServer self)
 void
 IedServer_lockDataModel(IedServer self)
 {
+    Semaphore_wait(self->mmsMapping->isModelLockedMutex);
+
     MmsServer_lockModel(self->mmsServer);
 
     self->mmsMapping->isModelLocked = true;
+
+    Semaphore_post(self->mmsMapping->isModelLockedMutex);
 }
 
 void
@@ -827,9 +831,13 @@ IedServer_unlockDataModel(IedServer self)
     /* check if reports have to be sent! */
     Reporting_processReportEventsAfterUnlock(self->mmsMapping);
 
+    Semaphore_wait(self->mmsMapping->isModelLockedMutex);
+
     self->mmsMapping->isModelLocked = false;
 
     MmsServer_unlockModel(self->mmsServer);
+
+    Semaphore_post(self->mmsMapping->isModelLockedMutex);
 }
 
 #if (CONFIG_IEC61850_CONTROL_SERVICE == 1)
diff --git a/src/iec61850/server/mms_mapping/mms_mapping.c b/src/iec61850/server/mms_mapping/mms_mapping.c
index ff7a490f..5608edb8 100644
--- a/src/iec61850/server/mms_mapping/mms_mapping.c
+++ b/src/iec61850/server/mms_mapping/mms_mapping.c
@@ -2029,6 +2029,12 @@ MmsMapping_create(IedModel* model, IedServer iedServer)
     self->settingGroups = LinkedList_create();
 #endif
 
+    self->isModelLocked = false;
+
+#if (CONFIG_MMS_THREADLESS_STACK != 1)
+    self->isModelLockedMutex = Semaphore_create(1);
+#endif
+
     self->attributeAccessHandlers = LinkedList_create();
 
     /* create data model specification */
@@ -2119,6 +2125,10 @@ MmsMapping_destroy(MmsMapping* self)
     if (self->locbTrk) GLOBAL_FREEMEM(self->locbTrk);
 #endif
 
+#if (CONFIG_MMS_THREADLESS_STACK != 1)
+    Semaphore_destroy(self->isModelLockedMutex);
+#endif
+
     LinkedList_destroy(self->attributeAccessHandlers);
 
     IedModel_setAttributeValuesToNull(self->model);
@@ -3654,6 +3664,8 @@ MmsMapping_triggerReportObservers(MmsMapping* self, MmsValue* value, int flag)
 {
     LinkedList element = self->reportControls;
 
+    Semaphore_wait(self->isModelLockedMutex);
+
     bool modelLocked = self->isModelLocked;
 
     while ((element = LinkedList_getNext(element)) != NULL) {
@@ -3689,6 +3701,8 @@ MmsMapping_triggerReportObservers(MmsMapping* self, MmsValue* value, int flag)
     if (modelLocked == false) {
         Reporting_processReportEventsAfterUnlock(self);
     }
+
+    Semaphore_post(self->isModelLockedMutex);
 }
 
 #endif /* (CONFIG_IEC61850_REPORT_SERVICE == 1) */
@@ -3700,8 +3714,6 @@ MmsMapping_triggerGooseObservers(MmsMapping* self, MmsValue* value)
 {
     LinkedList element = self->gseControls;
 
-    bool modelLocked = self->isModelLocked;
-
     while ((element = LinkedList_getNext(element)) != NULL) {
         MmsGooseControlBlock gcb = (MmsGooseControlBlock) element->data;
 
@@ -3711,9 +3723,13 @@ MmsMapping_triggerGooseObservers(MmsMapping* self, MmsValue* value)
             if (DataSet_isMemberValue(dataSet, value, NULL)) {
                 MmsGooseControlBlock_setStateChangePending(gcb);
 
-                if (modelLocked == false) {
+                Semaphore_wait(self->isModelLockedMutex);
+
+                if (self->isModelLocked == false) {
                     MmsGooseControlBlock_publishNewState(gcb);
                 }
+
+                Semaphore_post(self->isModelLockedMutex);
             }
         }
     }
diff --git a/src/iec61850/server/mms_mapping/reporting.c b/src/iec61850/server/mms_mapping/reporting.c
index 91f1c004..27dd05fc 100644
--- a/src/iec61850/server/mms_mapping/reporting.c
+++ b/src/iec61850/server/mms_mapping/reporting.c
@@ -3062,10 +3062,6 @@ enqueueReport(ReportControl* reportControl, bool isIntegrity, bool isGI, uint64_
 
 exit_function:
 
-    if (overflow) {
-        /* TODO call user callback handler */
-    }
-
 #if (CONFIG_MMS_THREADLESS_STACK != 1)
     Semaphore_post(buffer->lock);
 #endif
@@ -3819,6 +3815,8 @@ processEventsForReport(ReportControl* rc, uint64_t currentTimeInMs)
 void
 Reporting_processReportEvents(MmsMapping* self, uint64_t currentTimeInMs)
 {
+    Semaphore_wait(self->isModelLockedMutex);
+
     if (self->isModelLocked == false) {
 
         LinkedList element = self->reportControls;
@@ -3833,6 +3831,8 @@ Reporting_processReportEvents(MmsMapping* self, uint64_t currentTimeInMs)
             ReportControl_unlockNotify(rc);
         }
     }
+
+    Semaphore_post(self->isModelLockedMutex);
 }
 
 /*