diff --git a/examples/contrib/volsay.cs b/examples/contrib/volsay.cs
index b6f13432d8..cfd17c5118 100644
--- a/examples/contrib/volsay.cs
+++ b/examples/contrib/volsay.cs
@@ -29,7 +29,11 @@ public class Volsay
      */
     private static void Solve()
     {
-        Solver solver = new Solver("Volsay", Solver.OptimizationProblemType.CLP_LINEAR_PROGRAMMING);
+        Solver solver = Solver.CreateSolver("CLP");
+        if (solver is null)
+        {
+            return;
+        }
 
         //
         // Variables
diff --git a/examples/contrib/volsay2.cs b/examples/contrib/volsay2.cs
index 60c89f73cf..5e63922e02 100644
--- a/examples/contrib/volsay2.cs
+++ b/examples/contrib/volsay2.cs
@@ -31,7 +31,11 @@ public class Volsay2
      */
     private static void Solve()
     {
-        Solver solver = new Solver("Volsay2", Solver.OptimizationProblemType.CLP_LINEAR_PROGRAMMING);
+        Solver solver = Solver.CreateSolver("CLP");
+        if (solver is null)
+        {
+            return;
+        }
 
         int num_products = 2;
         IEnumerable<int> PRODUCTS = Enumerable.Range(0, num_products);
diff --git a/examples/contrib/volsay3.cs b/examples/contrib/volsay3.cs
index 180dfe1d22..d0481d9b0f 100644
--- a/examples/contrib/volsay3.cs
+++ b/examples/contrib/volsay3.cs
@@ -32,7 +32,11 @@ public class Volsay3
      */
     private static void Solve()
     {
-        Solver solver = new Solver("Volsay3", Solver.OptimizationProblemType.CLP_LINEAR_PROGRAMMING);
+        Solver solver = Solver.CreateSolver("CLP");
+        if (solver is null)
+        {
+            return;
+        }
 
         int num_products = 2;
         IEnumerable<int> PRODUCTS = Enumerable.Range(0, num_products);
diff --git a/examples/tests/LinearSolverTests.cs b/examples/tests/LinearSolverTests.cs
index 1ea51350dc..515143e177 100644
--- a/examples/tests/LinearSolverTests.cs
+++ b/examples/tests/LinearSolverTests.cs
@@ -23,6 +23,10 @@ public class LinearSolverTest
     public void VarOperator()
     {
         Solver solver = Solver.CreateSolver("CLP");
+        if (solver is null)
+        {
+            return;
+        }
         Variable x = solver.MakeNumVar(0.0, 100.0, "x");
         Assert.Equal(0.0, x.Lb());
         Assert.Equal(100.0, x.Ub());
@@ -62,6 +66,10 @@ public class LinearSolverTest
     public void VarAddition()
     {
         Solver solver = Solver.CreateSolver("CLP");
+        if (solver is null)
+        {
+            return;
+        }
         Variable x = solver.MakeNumVar(0.0, 100.0, "x");
         Assert.Equal(0.0, x.Lb());
         Assert.Equal(100.0, x.Ub());
@@ -92,6 +100,10 @@ public class LinearSolverTest
     public void VarMultiplication()
     {
         Solver solver = Solver.CreateSolver("CLP");
+        if (solver is null)
+        {
+            return;
+        }
         Variable x = solver.MakeNumVar(0.0, 100.0, "x");
         Assert.Equal(0.0, x.Lb());
         Assert.Equal(100.0, x.Ub());
@@ -127,6 +139,10 @@ public class LinearSolverTest
     public void BinaryOperator()
     {
         Solver solver = Solver.CreateSolver("CLP");
+        if (solver is null)
+        {
+            return;
+        }
         Variable x = solver.MakeNumVar(0.0, 100.0, "x");
         Assert.Equal(0.0, x.Lb());
         Assert.Equal(100.0, x.Ub());
@@ -161,6 +177,10 @@ public class LinearSolverTest
     public void Inequalities()
     {
         Solver solver = Solver.CreateSolver("CLP");
+        if (solver is null)
+        {
+            return;
+        }
         Variable x = solver.MakeNumVar(0.0, 100.0, "x");
         Assert.Equal(0.0, x.Lb());
         Assert.Equal(100.0, x.Ub());
@@ -198,6 +218,10 @@ public class LinearSolverTest
     public void SumArray()
     {
         Solver solver = Solver.CreateSolver("CLP");
+        if (solver is null)
+        {
+            return;
+        }
 
         Variable[] x = solver.MakeBoolVarArray(10, "x");
         Constraint ct1 = solver.Add(x.Sum() == 3);
@@ -217,6 +241,10 @@ public class LinearSolverTest
     public void Objective()
     {
         Solver solver = Solver.CreateSolver("CLP");
+        if (solver is null)
+        {
+            return;
+        }
         Variable x = solver.MakeNumVar(0.0, 100.0, "x");
         Assert.Equal(0.0, x.Lb());
         Assert.Equal(100.0, x.Ub());
@@ -279,7 +307,7 @@ public class LinearSolverTest
         Console.WriteLine($"------ Linear programming example with {problemType} ------");
 
         Solver solver = Solver.CreateSolver(problemType);
-        if (solver == null)
+        if (solver is null)
             return;
 
         // x and y are continuous non-negative variables.
diff --git a/ortools/linear_solver/samples/AssignmentGroupsMip.cs b/ortools/linear_solver/samples/AssignmentGroupsMip.cs
index ae9b8d8011..c833c95a47 100644
--- a/ortools/linear_solver/samples/AssignmentGroupsMip.cs
+++ b/ortools/linear_solver/samples/AssignmentGroupsMip.cs
@@ -59,6 +59,10 @@ public class AssignmentGroupsMip
         // Solver.
         // [START solver]
         Solver solver = Solver.CreateSolver("SCIP");
+        if (solver is null)
+        {
+            return;
+        }
         // [END solver]
 
         // Variables.
diff --git a/ortools/linear_solver/samples/AssignmentMip.cs b/ortools/linear_solver/samples/AssignmentMip.cs
index 1c8ea33a48..0fea30ad05 100644
--- a/ortools/linear_solver/samples/AssignmentMip.cs
+++ b/ortools/linear_solver/samples/AssignmentMip.cs
@@ -33,6 +33,10 @@ public class AssignmentMip
         // Solver.
         // [START solver]
         Solver solver = Solver.CreateSolver("SCIP");
+        if (solver is null)
+        {
+            return;
+        }
         // [END solver]
 
         // Variables.
diff --git a/ortools/linear_solver/samples/AssignmentTaskSizesMip.cs b/ortools/linear_solver/samples/AssignmentTaskSizesMip.cs
index 06304726d5..0bba6ab154 100644
--- a/ortools/linear_solver/samples/AssignmentTaskSizesMip.cs
+++ b/ortools/linear_solver/samples/AssignmentTaskSizesMip.cs
@@ -46,6 +46,10 @@ public class AssignmentTaskSizesMip
         // Solver.
         // [START solver]
         Solver solver = Solver.CreateSolver("SCIP");
+        if (solver is null)
+        {
+            return;
+        }
         // [END solver]
 
         // Variables.
diff --git a/ortools/linear_solver/samples/AssignmentTeamsMip.cs b/ortools/linear_solver/samples/AssignmentTeamsMip.cs
index 677683c08a..69870c3c1c 100644
--- a/ortools/linear_solver/samples/AssignmentTeamsMip.cs
+++ b/ortools/linear_solver/samples/AssignmentTeamsMip.cs
@@ -44,6 +44,10 @@ public class AssignmentTeamsMip
         // Solver.
         // [START solver]
         Solver solver = Solver.CreateSolver("SCIP");
+        if (solver is null)
+        {
+            return;
+        }
         // [END solver]
 
         // Variables.
diff --git a/ortools/linear_solver/samples/BasicExample.cs b/ortools/linear_solver/samples/BasicExample.cs
index 549816aa5d..e41192f646 100644
--- a/ortools/linear_solver/samples/BasicExample.cs
+++ b/ortools/linear_solver/samples/BasicExample.cs
@@ -23,6 +23,10 @@ public class BasicExample
         // [START solver]
         // Create the linear solver with the GLOP backend.
         Solver solver = Solver.CreateSolver("GLOP");
+        if (solver is null)
+        {
+            return;
+        }
         // [END solver]
 
         // [START variables]
diff --git a/ortools/linear_solver/samples/BinPackingMip.cs b/ortools/linear_solver/samples/BinPackingMip.cs
index 4668b1c030..4e7e4af610 100644
--- a/ortools/linear_solver/samples/BinPackingMip.cs
+++ b/ortools/linear_solver/samples/BinPackingMip.cs
@@ -39,6 +39,10 @@ public class BinPackingMip
         // [START solver]
         // Create the linear solver with the SCIP backend.
         Solver solver = Solver.CreateSolver("SCIP");
+        if (solver is null)
+        {
+            return;
+        }
         // [END solver]
 
         // [START program_part2]
diff --git a/ortools/linear_solver/samples/LinearProgrammingExample.cs b/ortools/linear_solver/samples/LinearProgrammingExample.cs
index 98495bf44a..b2dbefd772 100644
--- a/ortools/linear_solver/samples/LinearProgrammingExample.cs
+++ b/ortools/linear_solver/samples/LinearProgrammingExample.cs
@@ -23,6 +23,10 @@ public class LinearProgrammingExample
     {
         // [START solver]
         Solver solver = Solver.CreateSolver("GLOP");
+        if (solver is null)
+        {
+            return;
+        }
         // [END solver]
         // x and y are continuous non-negative variables.
         // [START variables]
diff --git a/ortools/linear_solver/samples/MipVarArray.cs b/ortools/linear_solver/samples/MipVarArray.cs
index a68f1df0ab..2646708bc0 100644
--- a/ortools/linear_solver/samples/MipVarArray.cs
+++ b/ortools/linear_solver/samples/MipVarArray.cs
@@ -45,6 +45,10 @@ public class MipVarArray
         // [START solver]
         // Create the linear solver with the SCIP backend.
         Solver solver = Solver.CreateSolver("SCIP");
+        if (solver is null)
+        {
+            return;
+        }
         // [END solver]
 
         // [START program_part2]
diff --git a/ortools/linear_solver/samples/MultipleKnapsackMip.cs b/ortools/linear_solver/samples/MultipleKnapsackMip.cs
index 3f1f76b202..10d48165d5 100644
--- a/ortools/linear_solver/samples/MultipleKnapsackMip.cs
+++ b/ortools/linear_solver/samples/MultipleKnapsackMip.cs
@@ -39,6 +39,10 @@ public class MultipleKnapsackMip
         // [START solver]
         // Create the linear solver with the SCIP backend.
         Solver solver = Solver.CreateSolver("SCIP");
+        if (solver is null)
+        {
+            return;
+        }
         // [END solver]
 
         // Variables.
diff --git a/ortools/linear_solver/samples/SimpleLpProgram.cs b/ortools/linear_solver/samples/SimpleLpProgram.cs
index 62e4712db9..59e070d79d 100644
--- a/ortools/linear_solver/samples/SimpleLpProgram.cs
+++ b/ortools/linear_solver/samples/SimpleLpProgram.cs
@@ -25,6 +25,10 @@ public class SimpleLpProgram
         // [START solver]
         // Create the linear solver with the GLOP backend.
         Solver solver = Solver.CreateSolver("GLOP");
+        if (solver is null)
+        {
+            return;
+        }
         // [END solver]
 
         // [START variables]
diff --git a/ortools/linear_solver/samples/SimpleMipProgram.cs b/ortools/linear_solver/samples/SimpleMipProgram.cs
index 14a5beb6a2..c4f6c3c7c4 100644
--- a/ortools/linear_solver/samples/SimpleMipProgram.cs
+++ b/ortools/linear_solver/samples/SimpleMipProgram.cs
@@ -24,6 +24,10 @@ public class SimpleMipProgram
         // [START solver]
         // Create the linear solver with the SCIP backend.
         Solver solver = Solver.CreateSolver("SCIP");
+        if (solver is null)
+        {
+            return;
+        }
         // [END solver]
 
         // [START variables]
diff --git a/ortools/linear_solver/samples/StiglerDiet.cs b/ortools/linear_solver/samples/StiglerDiet.cs
index 72e0268664..8f708d62fb 100644
--- a/ortools/linear_solver/samples/StiglerDiet.cs
+++ b/ortools/linear_solver/samples/StiglerDiet.cs
@@ -114,6 +114,10 @@ public class StiglerDiet
         // [START solver]
         // Create the linear solver with the GLOP backend.
         Solver solver = Solver.CreateSolver("GLOP");
+        if (solver is null)
+        {
+            return;
+        }
         // [END solver]
 
         // [START variables]