diff --git a/packages/CLPBN/horus/BayesBallGraph.cpp b/packages/CLPBN/horus/BayesBallGraph.cpp
index 626d940d9..6fd95e44e 100644
--- a/packages/CLPBN/horus/BayesBallGraph.cpp
+++ b/packages/CLPBN/horus/BayesBallGraph.cpp
@@ -81,7 +81,7 @@ BayesBallGraph::exportToGraphViz (const char* fileName)
   if (!out.is_open()) {
     cerr << "error: cannot open file to write at " ;
     cerr << "BayesBallGraph::exportToDotFile()" << endl;
-    abort();
+    return;
   }
   out << "digraph {" << endl;
   out << "ranksep=1" << endl;
diff --git a/packages/CLPBN/horus/ConstraintTree.cpp b/packages/CLPBN/horus/ConstraintTree.cpp
index 6dad4c87e..33107e101 100644
--- a/packages/CLPBN/horus/ConstraintTree.cpp
+++ b/packages/CLPBN/horus/ConstraintTree.cpp
@@ -523,7 +523,7 @@ ConstraintTree::exportToGraphViz (
   if (!out.is_open()) {
     cerr << "error: cannot open file to write at " ;
     cerr << "ConstraintTree::exportToDotFile()" << endl;
-    abort();
+    return;
   }
   out << "digraph {" << endl;
   ConstraintTree copy (*this);
diff --git a/packages/CLPBN/horus/ElimGraph.cpp b/packages/CLPBN/horus/ElimGraph.cpp
index 93c8527e4..48d360da8 100644
--- a/packages/CLPBN/horus/ElimGraph.cpp
+++ b/packages/CLPBN/horus/ElimGraph.cpp
@@ -101,17 +101,14 @@ ElimGraph::exportToGraphViz (
   if (!out.is_open()) {
     cerr << "error: cannot open file to write at " ;
     cerr << "Markov::exportToDotFile()" << endl;
-    abort();
+    return;
   }
-
   out << "strict graph {" << endl;
-
   for (size_t i = 0; i < nodes_.size(); i++) {
     if (showNeighborless || nodes_[i]->neighbors().size() != 0) {
       out << '"' << nodes_[i]->label() << '"' << endl;
     }
   }
-
   for (size_t i = 0; i < highlightVarIds.size(); i++) {
     EgNode* node =getEgNode (highlightVarIds[i]);
     if (node) {
@@ -122,7 +119,6 @@ ElimGraph::exportToGraphViz (
       abort();
     }
   }
-
   for (size_t i = 0; i < nodes_.size(); i++) {
     EGNeighs neighs = nodes_[i]->neighbors();
     for (size_t j = 0; j < neighs.size(); j++) {
@@ -130,7 +126,6 @@ ElimGraph::exportToGraphViz (
       out << '"' << neighs[j]->label() << '"' << endl;
     }
   }
-
   out << "}" << endl;
   out.close();
 }
diff --git a/packages/CLPBN/horus/FactorGraph.cpp b/packages/CLPBN/horus/FactorGraph.cpp
index 417499c4d..5badec4ca 100644
--- a/packages/CLPBN/horus/FactorGraph.cpp
+++ b/packages/CLPBN/horus/FactorGraph.cpp
@@ -283,7 +283,7 @@ FactorGraph::exportToGraphViz (const char* fileName) const
   if (!out.is_open()) {
     cerr << "error: cannot open file to write at " ;
     cerr << "FactorGraph::exportToDotFile()" << endl;
-    abort();
+    return;
   }
   out << "graph \"" << fileName << "\" {" << endl;
   for (size_t i = 0; i < varNodes_.size(); i++) {
@@ -316,8 +316,9 @@ FactorGraph::exportToUaiFormat (const char* fileName) const
 {
   ofstream out (fileName);
   if (!out.is_open()) {
-    cerr << "error: cannot open file " << fileName << endl;
-    abort();
+    cerr << "error: cannot open file to write at " ;
+    cerr << "ConstraintTree::exportToUaiFormat()" << endl;
+    return;
   }
   out << "MARKOV" << endl;
   out << varNodes_.size() << endl;
@@ -350,8 +351,9 @@ FactorGraph::exportToLibDaiFormat (const char* fileName) const
 {
   ofstream out (fileName);
   if (!out.is_open()) {
-    cerr << "error: cannot open file " << fileName << endl;
-    abort();
+    cerr << "error: cannot open file to write at " ;
+    cerr << "ConstraintTree::exportToUaiFormat()" << endl;
+    return;
   }
   out << facNodes_.size() << endl << endl;
   for (size_t i = 0; i < facNodes_.size(); i++) {
diff --git a/packages/CLPBN/horus/LiftedCircuit.cpp b/packages/CLPBN/horus/LiftedCircuit.cpp
index a31b22692..094e04aab 100644
--- a/packages/CLPBN/horus/LiftedCircuit.cpp
+++ b/packages/CLPBN/horus/LiftedCircuit.cpp
@@ -278,8 +278,8 @@ LiftedCircuit::exportToGraphViz (const char* fileName)
   ofstream out (fileName);
   if (!out.is_open()) {
     cerr << "error: cannot open file to write at " ;
-    cerr << "BayesBallGraph::exportToDotFile()" << endl;
-    abort();
+    cerr << "LiftedCircuit::exportToDotFile()" << endl;
+    return;
   }
   out << "digraph {" << endl;
   out << "ranksep=1" << endl;