From 344d8e72986148c54296ceb9e826e4edee5a08f8 Mon Sep 17 00:00:00 2001
From: Valeri Karpov <val@karpov.io>
Date: Fri, 28 Nov 2025 12:57:28 -0500
Subject: [PATCH 1/2] fix(model): bump version if necessary after successful
 bulkSave()

Fix #15800
---
 lib/document.js    | 16 ++++++++++++++++
 lib/model.js       | 13 +++++--------
 test/model.test.js | 47 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 68 insertions(+), 8 deletions(-)

diff --git a/lib/document.js b/lib/document.js
index 15764c7568..cd0ca2d326 100644
--- a/lib/document.js
+++ b/lib/document.js
@@ -5422,6 +5422,22 @@ Document.prototype.$__hasOnlyPrimitiveValues = function $__hasOnlyPrimitiveValue
   }));
 };
 
+/*!
+ * Increment this document's version if necessary.
+ */
+
+Document.prototype._applyVersionIncrement = function _applyVersionIncrement() {
+  if (!this.$__.version) return;
+  const doIncrement = VERSION_INC === (VERSION_INC & this.$__.version);
+
+  this.$__.version = undefined;
+  if (doIncrement) {
+    const key = this.$__schema.options.versionKey;
+    const version = this.$__getValue(key) || 0;// increment version if was successful
+    this.$__setValue(key, version + 1);
+  }
+};
+
 /*!
  * Module exports.
  */
diff --git a/lib/model.js b/lib/model.js
index 67f017b6a4..e7247344a5 100644
--- a/lib/model.js
+++ b/lib/model.js
@@ -523,11 +523,9 @@ Model.prototype.$__save = function(options, callback) {
       const versionBump = this.$__.version;
       // was this an update that required a version bump?
       if (versionBump && !this.$__.inserting) {
-        const doIncrement = VERSION_INC === (VERSION_INC & this.$__.version);
-        this.$__.version = undefined;
-        const key = this.$__schema.options.versionKey;
-        const version = this.$__getValue(key) || 0;
         if (numAffected <= 0) {
+          const key = this.$__schema.options.versionKey;
+          const version = this.$__getValue(key) || 0;
           // the update failed. pass an error back
           this.$__undoReset();
           const err = this.$__.$versionError ||
@@ -535,10 +533,7 @@ Model.prototype.$__save = function(options, callback) {
           return callback(err, this);
         }
 
-        // increment version if was successful
-        if (doIncrement) {
-          this.$__setValue(key, version + 1);
-        }
+        this._applyVersionIncrement();
       }
       if (result != null && numAffected <= 0) {
         this.$__undoReset();
@@ -3666,6 +3661,8 @@ function handleSuccessfulWrite(document) {
     }
 
     document.$__reset();
+    document._applyVersionIncrement();
+
     document.schema.s.hooks.execPost('save', document, [document], {}, (err) => {
       if (err) {
         reject(err);
diff --git a/test/model.test.js b/test/model.test.js
index cb28be62aa..264e59f90a 100644
--- a/test/model.test.js
+++ b/test/model.test.js
@@ -7015,6 +7015,53 @@ describe('Model', function() {
       );
     });
 
+    it('increments version key on successful save (gh-15800)', async function() {
+      // Arrange
+      const userSchema = new Schema({
+        name: [String],
+        email: { type: String, minLength: 3 }
+      });
+
+      const User = db.model('User', userSchema);
+      const user1 = new User({ name: ['123'], email: '12314' });
+      await user1.save();
+
+      // Act
+      const user = await User.findOne({ _id: user1._id });
+      assert.ok(user);
+
+      // Before, __v should be 0
+      assert.equal(user.__v, 0);
+
+      // markModified on array field (triggers $set)
+      user.markModified('name');
+      await User.bulkSave([user]);
+
+      const dbUser1 = await User.findById(user._id);
+      assert.equal(dbUser1.__v, 1);
+      assert.equal(user.__v, 1);
+
+      // Update another path and markModified
+      user.email = '1375';
+      await User.bulkSave([user]);
+      const dbUser2 = await User.findById(user._id);
+      assert.equal(dbUser2.__v, 1);
+      assert.equal(user.__v, 1);
+
+      let reloaded = await User.findById(user._id);
+      assert.equal(reloaded.__v, 1);
+
+      user.email = '1';
+      await assert.rejects(
+        () => User.bulkSave([user]),
+        /email.*is shorter than the minimum allowed length/
+      );
+      assert.equal(user.__v, 1);
+
+      reloaded = await User.findById(user._id);
+      assert.equal(reloaded.__v, 1);
+    });
+
     it('saves new documents with ordered: false (gh-15495)', async function() {
       const userSchema = new Schema({
         name: { type: String }

From 7a305a8b5b60437714a5110fae8ddb34e6ed679c Mon Sep 17 00:00:00 2001
From: Valeri Karpov <val@karpov.io>
Date: Mon, 1 Dec 2025 17:37:36 -0500
Subject: [PATCH 2/2] Update lib/document.js

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
---
 lib/document.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/document.js b/lib/document.js
index cd0ca2d326..e9b1e63e90 100644
--- a/lib/document.js
+++ b/lib/document.js
@@ -5433,8 +5433,8 @@ Document.prototype._applyVersionIncrement = function _applyVersionIncrement() {
   this.$__.version = undefined;
   if (doIncrement) {
     const key = this.$__schema.options.versionKey;
-    const version = this.$__getValue(key) || 0;// increment version if was successful
-    this.$__setValue(key, version + 1);
+    const version = this.$__getValue(key) || 0;
+    this.$__setValue(key, version + 1); // increment version if was successful
   }
 };