diff --git a/.travis.yml b/.travis.yml
index 5723a41f8..c93c1d2ce 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,6 +19,8 @@ script:
   - if [[ "$TRAVIS_OS_NAME" == "linux" && "$CXX" = "g++" ]]; then sudo pip3 install setuptools; fi
   - if [[ "$TRAVIS_OS_NAME" == "linux" && "$CXX" = "g++" ]]; then sudo python3 setup.py install; fi
   - if [[ "$TRAVIS_OS_NAME" == "linux" && "$CXX" = "g++" ]]; then python3 examples/pybullet/unittests/unittests.py --verbose; fi
+  - if [[ "$TRAVIS_OS_NAME" == "linux" && "$CXX" = "g++" ]]; then python3 examples/pybullet/unittests/userDataTest.py --verbose; fi
+  - if [[ "$TRAVIS_OS_NAME" == "linux" && "$CXX" = "g++" ]]; then python3 examples/pybullet/unittests/saveRestoreStateTest.py --verbose; fi
   - cmake . -DBUILD_PYBULLET=ON -G"Unix Makefiles" #-DCMAKE_CXX_FLAGS=-Werror
   - make -j8
   - ctest -j8 --output-on-failure
diff --git a/examples/pybullet/pybullet.c b/examples/pybullet/pybullet.c
index a92bb5240..b2ef1027a 100644
--- a/examples/pybullet/pybullet.c
+++ b/examples/pybullet/pybullet.c
@@ -820,8 +820,8 @@ static PyObject* pybullet_getUserData(PyObject* self, PyObject* args, PyObject*
 
 	if (!b3GetUserData(sm, bodyUniqueId, linkIndex, userDataId, &value)) {
 		
-		PyErr_SetString(SpamError, "Cannot get user data");
-		return NULL;
+		Py_INCREF(Py_None);
+		return Py_None;
 	}
 	if (value.m_type != USER_DATA_VALUE_TYPE_STRING) 
 	{
diff --git a/examples/pybullet/unittests/saveRestoreStateTest.py b/examples/pybullet/unittests/saveRestoreStateTest.py
new file mode 100644
index 000000000..da3480904
--- /dev/null
+++ b/examples/pybullet/unittests/saveRestoreStateTest.py
@@ -0,0 +1,144 @@
+import unittest
+import pybullet as p
+import math, time
+import difflib,sys
+
+from utils import allclose, dot
+
+class TestPybulletSaveRestoreMethods(unittest.TestCase):
+
+	def setupWorld(self):
+		numObjects = 50
+		
+		
+		maximalCoordinates = False
+
+		p.resetSimulation()
+		p.setPhysicsEngineParameter(deterministicOverlappingPairs=1)
+		p.loadURDF("planeMesh.urdf",useMaximalCoordinates=maximalCoordinates)
+		kukaId = p.loadURDF("kuka_iiwa/model_free_base.urdf",[0,0,10], useMaximalCoordinates=maximalCoordinates)
+		for i in range (p.getNumJoints(kukaId)):
+			p.setJointMotorControl2(kukaId,i,p.POSITION_CONTROL,force=0)
+		for i in range (numObjects):
+			cube = p.loadURDF("cube_small.urdf",[0,i*0.02,(i+1)*0.2])
+			#p.changeDynamics(cube,-1,mass=100)
+		p.stepSimulation()
+		p.setGravity(0,0,-10)
+
+
+	def dumpStateToFile(self, file):
+		for i in  range (p.getNumBodies()):
+			pos,orn = p.getBasePositionAndOrientation(i)
+			linVel,angVel = p.getBaseVelocity(i)
+			txtPos = "pos="+str(pos)+"\n"
+			txtOrn = "orn="+str(orn)+"\n"
+			txtLinVel = "linVel"+str(linVel)+"\n"
+			txtAngVel = "angVel"+str(angVel)+"\n"
+			file.write(txtPos)
+			file.write(txtOrn)
+			file.write(txtLinVel)
+			file.write(txtAngVel)
+		
+	def compareFiles(self, file1,file2):
+		diff = difflib.unified_diff(
+	            file1.readlines(),
+	            file2.readlines(),
+	            fromfile='saveFile.txt',
+	            tofile='restoreFile.txt',
+	        )
+		numDifferences = 0
+		for line in diff:
+			numDifferences = numDifferences+1
+			sys.stdout.write(line)
+		self.assertEqual(numDifferences,0)
+		
+
+	def testSaveRestoreState(self):
+		numSteps = 500
+		numSteps2 = 30
+
+		
+		verbose = 0
+		self.setupWorld()
+		
+
+		for i in range (numSteps):
+			p.stepSimulation()	
+		p.saveBullet("state.bullet")
+		if verbose:
+			p.setInternalSimFlags(1)
+		p.stepSimulation()
+		if verbose:
+			p.setInternalSimFlags(0)
+			print("contact points=")
+			for q in p.getContactPoints():
+				print(q)
+
+		for i in range (numSteps2):
+			p.stepSimulation()
+
+
+		file = open("saveFile.txt","w") 
+		self.dumpStateToFile(file)
+		file.close() 
+
+		#################################
+		self.setupWorld()
+
+		#both restore from file or from in-memory state should work
+		p.restoreState(fileName="state.bullet")
+		stateId = p.saveState()
+
+		if verbose:
+			p.setInternalSimFlags(1)
+		p.stepSimulation()
+		if verbose:
+			p.setInternalSimFlags(0)
+			print("contact points restored=")
+			for q in p.getContactPoints():
+				print(q)
+		for i in range (numSteps2):
+			p.stepSimulation()
+
+			
+		file = open("restoreFile.txt","w")
+		self.dumpStateToFile(file)
+		file.close() 
+
+		p.restoreState(stateId)
+		if verbose:
+			p.setInternalSimFlags(1)
+		p.stepSimulation()
+		if verbose:
+			p.setInternalSimFlags(0)
+			print("contact points restored=")
+			for q in p.getContactPoints():
+				print(q)
+		for i in range (numSteps2):
+			p.stepSimulation()
+
+			
+		file = open("restoreFile2.txt","w")
+		self.dumpStateToFile(file)
+		file.close() 
+
+		file1 = open("saveFile.txt","r") 
+		file2 = open("restoreFile.txt","r") 
+		self.compareFiles(file1,file2)
+		file1.close()
+		file2.close()
+
+		file1 = open("saveFile.txt","r") 
+		file2 = open("restoreFile2.txt","r") 
+		self.compareFiles(file1,file2)
+		file1.close()
+		file2.close()        
+
+		
+
+#while (p.getConnectionInfo()["isConnected"]):
+#	time.sleep(1)
+
+if __name__ == '__main__':
+	p.connect(p.DIRECT)
+	unittest.main()
diff --git a/src/BulletCollision/BroadphaseCollision/btDispatcher.h b/src/BulletCollision/BroadphaseCollision/btDispatcher.h
index a0e4c1892..d7a97e8e0 100644
--- a/src/BulletCollision/BroadphaseCollision/btDispatcher.h
+++ b/src/BulletCollision/BroadphaseCollision/btDispatcher.h
@@ -47,7 +47,7 @@ struct btDispatcherInfo
 		m_allowedCcdPenetration(btScalar(0.04)),
 		m_useConvexConservativeDistanceUtil(false),
 		m_convexConservativeDistanceThreshold(0.0f),
-		m_deterministicOverlappingPairs(false)
+		m_deterministicOverlappingPairs(true)
 	{
 
 	}
diff --git a/src/BulletCollision/CollisionDispatch/btCollisionDispatcher.cpp b/src/BulletCollision/CollisionDispatch/btCollisionDispatcher.cpp
index 5739a1ef0..af521ea9c 100644
--- a/src/BulletCollision/CollisionDispatch/btCollisionDispatcher.cpp
+++ b/src/BulletCollision/CollisionDispatch/btCollisionDispatcher.cpp
@@ -252,7 +252,15 @@ void	btCollisionDispatcher::dispatchAllCollisionPairs(btOverlappingPairCache* pa
 
 	btCollisionPairCallback	collisionCallback(dispatchInfo,this);
 
-	pairCache->processAllOverlappingPairs(&collisionCallback,dispatcher);
+	if (dispatchInfo.m_deterministicOverlappingPairs)
+	{
+		BT_PROFILE("sortOverlappingPairs");
+		pairCache->sortOverlappingPairs(this);
+	}
+	{
+		BT_PROFILE("processAllOverlappingPairs");
+		pairCache->processAllOverlappingPairs(&collisionCallback,dispatcher);
+	}
 
 	//m_blockedForChanges = false;