diff --git a/lib/model.js b/lib/model.js
index 7e983427e3c..88eff90b945 100644
--- a/lib/model.js
+++ b/lib/model.js
@@ -309,8 +309,14 @@ Model.prototype.$__handleSave = function(options, callback) {
         callback(null, ret);
       });
     } else {
-      this.$__reset();
-      callback();
+      this.constructor.exists(this.$__where())
+        .then((documentExists)=>{
+          if (!documentExists) throw new DocumentNotFoundError(this.$__where(),this.constructor.modelName);
+
+          this.$__reset();
+          callback();
+        })
+        .catch(callback);
       return;
     }
 
diff --git a/test/document.test.js b/test/document.test.js
index e3ee5e00ab4..a87e805b6b2 100644
--- a/test/document.test.js
+++ b/test/document.test.js
@@ -25,6 +25,7 @@ const SchemaType = mongoose.SchemaType;
 const ValidatorError = SchemaType.ValidatorError;
 const ValidationError = mongoose.Document.ValidationError;
 const MongooseError = mongoose.Error;
+const DocumentNotFoundError = mongoose.Error.DocumentNotFoundError;
 
 /**
  * Test Document constructor.
@@ -1939,6 +1940,95 @@ describe('document', function() {
     });
   });
 
+  describe('gh-8371', function() {
+    it('setting isNew to true makes save tries to insert a new document (gh-8371)', function() {
+      return co(function*() {
+        const personSchema = new Schema({ name: String });
+        const Person = db.model('gh8371-A', personSchema);
+
+        const createdPerson = yield Person.create({name:'Hafez'});
+        const removedPerson = yield Person.findOneAndRemove({_id:createdPerson._id});
+
+        removedPerson.isNew = true;
+
+        yield removedPerson.save();
+
+        const foundPerson = yield Person.findOne({_id:removedPerson._id});
+        assert.ok(foundPerson);
+      });
+    });
+
+    it('setting isNew to true throws an error when a document already exists (gh-8371)', function() {
+      return co(function*() {
+        const personSchema = new Schema({ name: String });
+        const Person = db.model('gh8371-B', personSchema);
+
+        const createdPerson = yield Person.create({name:'Hafez'});
+
+        createdPerson.isNew = true;
+
+        let threw = false;
+        try {
+          yield createdPerson.save();
+        }
+        catch (err) {
+          threw = true;
+          assert.equal(err.code, 11000);
+        }
+
+        assert.equal(threw,true);
+      });
+    });
+
+    it('saving a document with no changes, throws an error when document is not found', function() {
+      return co(function*() {
+        const personSchema = new Schema({ name: String });
+        const Person = db.model('gh8371-C', personSchema);
+
+        const person = yield Person.create({name:'Hafez'});
+
+        yield Person.deleteOne({_id:person._id});
+
+        let threw = false;
+        try {
+          yield person.save();
+        }
+        catch (err) {
+          assert.equal(err instanceof DocumentNotFoundError, true);
+          assert.equal(err.message,`No document found for query "{ _id: ${person._id} }" on model "gh8371-C"`);
+          threw = true;
+        }
+
+        assert.equal(threw,true);
+      });
+    });
+
+    it('saving a document with changes, throws an error when document is not found', function() {
+      return co(function*() {
+        const personSchema = new Schema({ name: String });
+        const Person = db.model('gh8371-D', personSchema);
+
+        const person = yield Person.create({name:'Hafez'});
+
+        yield Person.deleteOne({_id:person._id});
+
+        person.name = 'Different Name';
+
+        let threw = false;
+        try {
+          yield person.save();
+        }
+        catch (err) {
+          assert.equal(err instanceof DocumentNotFoundError,true);
+          assert.equal(err.message,`No document found for query "{ _id: ${person._id} }" on model "gh8371-D"`);
+          threw = true;
+        }
+
+        assert.equal(threw,true);
+      });
+    });
+  });
+
   it('properly calls queue functions (gh-2856)', function(done) {
     const personSchema = new mongoose.Schema({
       name: String
diff --git a/test/model.discriminator.querying.test.js b/test/model.discriminator.querying.test.js
index 83c55da1a8c..61db4e8344a 100644
--- a/test/model.discriminator.querying.test.js
+++ b/test/model.discriminator.querying.test.js
@@ -177,16 +177,10 @@ describe('model', function() {
       });
 
       describe('discriminator model only finds documents of its type', function() {
-        let impressionEvent, conversionEvent1, conversionEvent2;
-
-        before(function() {
-          impressionEvent = new ImpressionEvent({name: 'Impression event'});
-          conversionEvent1 = new ConversionEvent({name: 'Conversion event 1', revenue: 1});
-          conversionEvent2 = new ConversionEvent({name: 'Conversion event 2', revenue: 2});
-        });
 
         describe('using "ModelDiscriminator#findById"', function() {
           it('to find a document of the appropriate discriminator', function(done) {
+            const impressionEvent = new ImpressionEvent({name: 'Impression event'});
             impressionEvent.save(function(err) {
               assert.ifError(err);
 
@@ -217,6 +211,9 @@ describe('model', function() {
 
         describe('using "ModelDiscriminator#find"', function() {
           it('to find documents of the appropriate discriminator', function(done) {
+            const impressionEvent = new ImpressionEvent({name: 'Impression event'});
+            const conversionEvent1 = new ConversionEvent({name: 'Conversion event 1', revenue: 1});
+            const conversionEvent2 = new ConversionEvent({name: 'Conversion event 2', revenue: 2});
             impressionEvent.save(function(err) {
               assert.ifError(err);
               conversionEvent1.save(function(err) {