diff --git a/OndselSolver/ASMTGearJoint.cpp b/OndselSolver/ASMTGearJoint.cpp
index 00e1d99..e941ab0 100644
--- a/OndselSolver/ASMTGearJoint.cpp
+++ b/OndselSolver/ASMTGearJoint.cpp
@@ -9,6 +9,7 @@
 
 #include "ASMTGearJoint.h"
 #include "GearJoint.h"
+#include "SimulationStoppingError.h"
 
 using namespace MbD;
 
@@ -57,6 +58,7 @@ void MbD::ASMTGearJoint::readRadiusJ(std::vector<std::string>& lines)
 
 void MbD::ASMTGearJoint::createMbD(std::shared_ptr<System> mbdSys, std::shared_ptr<Units> mbdUnits)
 {
+	if (radiusI == 0.0 || radiusJ == 0.0) throw SimulationStoppingError("Gear radius is zero.");
 	ASMTJoint::createMbD(mbdSys, mbdUnits);
 	auto gearJoint = std::static_pointer_cast<GearJoint>(mbdObject);
 	gearJoint->radiusI = radiusI;
diff --git a/OndselSolver/ASMTRackPinionJoint.cpp b/OndselSolver/ASMTRackPinionJoint.cpp
index ae8b66f..f7470af 100644
--- a/OndselSolver/ASMTRackPinionJoint.cpp
+++ b/OndselSolver/ASMTRackPinionJoint.cpp
@@ -9,6 +9,7 @@
 
 #include "ASMTRackPinionJoint.h"
 #include "RackPinJoint.h"
+#include "SimulationStoppingError.h"
 
 using namespace MbD;
 
@@ -44,6 +45,7 @@ void MbD::ASMTRackPinionJoint::readPitchRadius(std::vector<std::string>& lines)
 
 void MbD::ASMTRackPinionJoint::createMbD(std::shared_ptr<System> mbdSys, std::shared_ptr<Units> mbdUnits)
 {
+	if (pitchRadius == 0.0) throw SimulationStoppingError("Rack pinion radius is zero.");
 	ASMTJoint::createMbD(mbdSys, mbdUnits);
 	auto rackPinJoint = std::static_pointer_cast<RackPinJoint>(mbdObject);
 	rackPinJoint->pitchRadius = pitchRadius;
diff --git a/OndselSolver/AccNewtonRaphson.cpp b/OndselSolver/AccNewtonRaphson.cpp
index 683df36..a690141 100644
--- a/OndselSolver/AccNewtonRaphson.cpp
+++ b/OndselSolver/AccNewtonRaphson.cpp
@@ -90,7 +90,7 @@ void AccNewtonRaphson::incrementIterNo()
 		str = ss.str();
 		system->logString(str);
 
-		throw SimulationStoppingError("");
+		throw SimulationStoppingError("iterNo > iterMax");
 	}
 }
 
diff --git a/OndselSolver/PosNewtonRaphson.cpp b/OndselSolver/PosNewtonRaphson.cpp
index 60edc7e..1d3140c 100644
--- a/OndselSolver/PosNewtonRaphson.cpp
+++ b/OndselSolver/PosNewtonRaphson.cpp
@@ -38,7 +38,7 @@ void PosNewtonRaphson::incrementIterNo()
 		str = ss.str();
 		system->logString(str);
 
-		throw SimulationStoppingError("");
+		throw SimulationStoppingError("iterNo > iterMax");
 	}	
 }
 
diff --git a/OndselSolver/QuasiIntegrator.cpp b/OndselSolver/QuasiIntegrator.cpp
index 9ec9480..cd63811 100644
--- a/OndselSolver/QuasiIntegrator.cpp
+++ b/OndselSolver/QuasiIntegrator.cpp
@@ -50,7 +50,7 @@ void QuasiIntegrator::run()
 				ss << "MbD: Check to see if a curve-curve is about to have multiple contact points." << std::endl;
 				auto str = ss.str();
 				this->logString(str);
-				throw SimulationStoppingError("");
+				throw SimulationStoppingError("singular matrix");
 			}
 		}
 		catch (TooSmallStepSizeError ex) {
@@ -61,7 +61,7 @@ void QuasiIntegrator::run()
 			ss << "MbD: If they are not, lower the permitted minimum step size." << std::endl;
 			auto str = ss.str();
 			this->logString(str);
-			throw SimulationStoppingError("");
+			throw SimulationStoppingError("stepSize < stepSizeMin");
 		}
 	}
 	catch (TooManyTriesError ex) {
@@ -69,7 +69,7 @@ void QuasiIntegrator::run()
 		ss << "MbD: Check to see if the error tolerance is too demanding." << std::endl;
 		auto str = ss.str();
 		this->logString(str);
-		throw SimulationStoppingError("");
+		throw SimulationStoppingError("iTry > iTryMax");
 	}
 
 }