diff --git a/arangod/Pregel/Algos/DMID/DMID.cpp b/arangod/Pregel/Algos/DMID/DMID.cpp
index d939372ef7..aef27a8793 100644
--- a/arangod/Pregel/Algos/DMID/DMID.cpp
+++ b/arangod/Pregel/Algos/DMID/DMID.cpp
@@ -634,6 +634,7 @@ GraphFormat<DMIDValue, float>* DMID::inputFormat() const {
 
 struct DMIDMasterContext : public MasterContext {
   DMIDMasterContext() {}  // TODO use _threashold
+  
   void preGlobalSuperstep() override {
     
     /**
diff --git a/arangod/Pregel/Conductor.cpp b/arangod/Pregel/Conductor.cpp
index 79f3145b17..3e21484518 100644
--- a/arangod/Pregel/Conductor.cpp
+++ b/arangod/Pregel/Conductor.cpp
@@ -460,7 +460,7 @@ static void resolveInfo(
     std::vector<ShardID>& allShards) {
   
   ServerState *ss = ServerState::instance();
-  if (!ss->isRunningInCluster()) {
+  if (!ss->isRunningInCluster()) { // single server mode
     LogicalCollection *lc = vocbase->lookupCollection(collectionID);
     if (lc == nullptr || lc->deleted()) {
       THROW_ARANGO_EXCEPTION_MESSAGE(TRI_ERROR_ARANGO_COLLECTION_NOT_FOUND,
diff --git a/arangod/Pregel/GraphStore.cpp b/arangod/Pregel/GraphStore.cpp
index 9cf7258379..d8198d32ab 100644
--- a/arangod/Pregel/GraphStore.cpp
+++ b/arangod/Pregel/GraphStore.cpp
@@ -122,8 +122,8 @@ void GraphStore<V, E>::loadShards(WorkerConfig* config,
       if (_loadedShards.find(vertexShards[i]) != _loadedShards.end()) {
         continue;
       }
-      ShardID const& vertexShard(vertexShards[i]);
-
+      
+      ShardID const& vertexShard = vertexShards[i];
       uint64_t nextEdgeOffset = edgeOffset;
       std::vector<ShardID> edgeLookups;
       // distributeshardslike should cause the edges for a vertex to be
@@ -326,8 +326,8 @@ void GraphStore<V, E>::_loadVertices(ShardID const& vertexShard,
         _graphFormat->copyVertexData(documentId, document, ptr, sizeof(V));
       }
       // load edges
-      for (ShardID const& it : edgeShards) {
-        _loadEdges(trx.get(), it, ventry, documentId);
+      for (ShardID const& edgeShard : edgeShards) {
+        _loadEdges(trx.get(), edgeShard, ventry, documentId);
       }
       vertexOffset++;
       edgeOffset += ventry._edgeCount;
@@ -403,9 +403,12 @@ void GraphStore<V, E>::_loadEdges(transaction::Methods* trx,
         _graphFormat->copyEdgeData(document, edge.data(), sizeof(E));
         if (sourceShard == (prgl_shard_t)-1 ||
             edge._targetShard == (prgl_shard_t)-1) {
+          LOG_TOPIC(ERR, Logger::PREGEL) << "Could not resolve target shard of edge";
           return;
         }
         offset++;
+      } else {
+        LOG_TOPIC(ERR, Logger::PREGEL) << "Could not resolve target shard of edge";
       }
     }
   };
diff --git a/arangod/Pregel/MasterContext.h b/arangod/Pregel/MasterContext.h
index 7f1bb2021e..30ada008ca 100644
--- a/arangod/Pregel/MasterContext.h
+++ b/arangod/Pregel/MasterContext.h
@@ -43,6 +43,7 @@ class MasterContext {
 
  public:
   MasterContext(){};
+  virtual ~MasterContext(){}
 
   inline uint64_t globalSuperstep() const { return _globalSuperstep; }
 
diff --git a/arangod/Pregel/Utils.cpp b/arangod/Pregel/Utils.cpp
index fe4c461ecf..acd435046a 100644
--- a/arangod/Pregel/Utils.cpp
+++ b/arangod/Pregel/Utils.cpp
@@ -127,9 +127,9 @@ int Utils::resolveShard(WorkerConfig const* config,
   partial.close();
   //  LOG_TOPIC(INFO, Logger::PREGEL) << "Partial doc: " << partial.toJson();
   int res =
-      ci->getResponsibleShard(info.get(), partial.slice(), true, responsibleShard,
+      ci->getResponsibleShard(info.get(), partial.slice(), false, responsibleShard,
                               usesDefaultShardingAttributes);
-  TRI_ASSERT(usesDefaultShardingAttributes);  // should be true anyway
+  //TRI_ASSERT(usesDefaultShardingAttributes);  // should be true anyway
   
   return res;
 }
diff --git a/arangod/Pregel/VertexComputation.h b/arangod/Pregel/VertexComputation.h
index 32aa223288..0128d82156 100644
--- a/arangod/Pregel/VertexComputation.h
+++ b/arangod/Pregel/VertexComputation.h
@@ -52,7 +52,7 @@ class VertexContext {
   VertexEntry* _vertexEntry;
 
  public:
-  ~VertexContext() {}
+  virtual ~VertexContext() {}
 
   template <typename T>
   inline void aggregate(std::string const& name, T const& value) {
@@ -105,6 +105,8 @@ class VertexComputation : public VertexContext<V, E, M> {
   bool _enterNextGSS = false;
 
  public:
+  virtual ~VertexComputation() {}
+  
   void sendMessage(Edge<E> const* edge, M const& data) {
     _cache->appendMessage(edge->targetShard(), edge->toKey(), data);
   }
@@ -140,6 +142,7 @@ class VertexCompensation : public VertexContext<V, E, M> {
   friend class Worker<V, E, M>;
 
  public:
+  virtual ~VertexCompensation() {}
   virtual void compensate(bool inLostPartition) = 0;
 };
 }