diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 97b6573d77e4..9f8f18d618c3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,7 +22,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ts-version: ["3.9", "4.0", "4.1"]
+        ts-version: ["3.9", "4.0", "4.1", "4.2", "4.3", "4.4", "4.5"]
     name: TS Typings (${{ matrix.ts-version }})
     runs-on: ubuntu-latest
     steps:
@@ -204,7 +204,7 @@ jobs:
         test-mysql-mariadb,
         test-mssql,
       ]
-    if: github.event_name == 'push' && github.ref == 'refs/heads/v6'
+    if: github.event_name == 'push' && (github.ref == 'refs/heads/v6' || github.ref == 'refs/heads/v6-alpha')
     env:
       GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
diff --git a/README.md b/README.md
index 3878c9b9e336..f8325b1f34de 100644
--- a/README.md
+++ b/README.md
@@ -67,3 +67,4 @@ If you have security issues to report, please refer to our [Responsible Disclosu
 
 - [English](https://sequelize.org/master) (OFFICIAL)
 - [中文文档](https://github.com/demopark/sequelize-docs-Zh-CN) (UNOFFICIAL)
+
diff --git a/lib/dialects/abstract/query-generator.js b/lib/dialects/abstract/query-generator.js
index 5a438cd3268b..5563771332ae 100644
--- a/lib/dialects/abstract/query-generator.js
+++ b/lib/dialects/abstract/query-generator.js
@@ -180,14 +180,33 @@ class QueryGenerator {
 
     let onDuplicateKeyUpdate = '';
 
+    // `options.updateOnDuplicate` is the list of field names to update if a duplicate key is hit during the insert.  It
+    // contains just the field names.  This option is _usually_ explicitly set by the corresponding query-interface
+    // upsert function.
     if (this._dialect.supports.inserts.updateOnDuplicate && options.updateOnDuplicate) {
       if (this._dialect.supports.inserts.updateOnDuplicate == ' ON CONFLICT DO UPDATE SET') { // postgres / sqlite
         // If no conflict target columns were specified, use the primary key names from options.upsertKeys
         const conflictKeys = options.upsertKeys.map(attr => this.quoteIdentifier(attr));
         const updateKeys = options.updateOnDuplicate.map(attr => `${this.quoteIdentifier(attr)}=EXCLUDED.${this.quoteIdentifier(attr)}`);
-        onDuplicateKeyUpdate = ` ON CONFLICT (${conflictKeys.join(',')}) DO UPDATE SET ${updateKeys.join(',')}`;
+        onDuplicateKeyUpdate = ` ON CONFLICT (${conflictKeys.join(',')})`;
+        // if update keys are provided, then apply them here.  if there are no updateKeys provided, then do not try to
+        // do an update.  Instead, fall back to DO NOTHING.
+        onDuplicateKeyUpdate += _.isEmpty(updateKeys.length) ? ' DO NOTHING ' : ` DO UPDATE SET ${updateKeys.join(',')}`;
       } else {
         const valueKeys = options.updateOnDuplicate.map(attr => `${this.quoteIdentifier(attr)}=VALUES(${this.quoteIdentifier(attr)})`);
+        // the rough equivalent to ON CONFLICT DO NOTHING in mysql, etc is ON DUPLICATE KEY UPDATE id = id
+        // So, if no update values were provided, fall back to the identifier columns provided in the upsertKeys array.
+        // This will be the primary key in most cases, but it could be some other constraint.
+        if (_.isEmpty(valueKeys) && options.upsertKeys) {
+          valueKeys.push(...options.upsertKeys.map(attr => `${this.quoteIdentifier(attr)}=${this.quoteIdentifier(attr)}`));
+        }
+
+        // edge case... but if for some reason there were no valueKeys, and there were also no upsertKeys... then we
+        // can no longer build the requested query without a syntax error.  Let's throw something more graceful here
+        // so the devs know what the problem is.
+        if (_.isEmpty(valueKeys)) {
+          throw new Error('No update values found for ON DUPLICATE KEY UPDATE clause, and no identifier fields could be found to use instead.');
+        }
         onDuplicateKeyUpdate += `${this._dialect.supports.inserts.updateOnDuplicate} ${valueKeys.join(',')}`;
       }
     }
@@ -286,6 +305,9 @@ class QueryGenerator {
       tuples.push(`(${values.join(',')})`);
     }
 
+    // `options.updateOnDuplicate` is the list of field names to update if a duplicate key is hit during the insert.  It
+    // contains just the field names.  This option is _usually_ explicitly set by the corresponding query-interface
+    // upsert function.
     if (this._dialect.supports.inserts.updateOnDuplicate && options.updateOnDuplicate) {
       if (this._dialect.supports.inserts.updateOnDuplicate == ' ON CONFLICT DO UPDATE SET') { // postgres / sqlite
         // If no conflict target columns were specified, use the primary key names from options.upsertKeys
diff --git a/lib/dialects/mssql/query-generator.js b/lib/dialects/mssql/query-generator.js
index 94e643ee0b23..3e44de52da72 100644
--- a/lib/dialects/mssql/query-generator.js
+++ b/lib/dialects/mssql/query-generator.js
@@ -449,7 +449,7 @@ class MSSQLQueryGenerator extends AbstractQueryGenerator {
 
     //IDENTITY_INSERT Condition
     identityAttrs.forEach(key => {
-      if (updateValues[key] && updateValues[key] !== null) {
+      if (insertValues[key] && insertValues[key] !== null) {
         needIdentityInsertWrapper = true;
         /*
          * IDENTITY_INSERT Column Cannot be updated, only inserted
@@ -501,16 +501,18 @@ class MSSQLQueryGenerator extends AbstractQueryGenerator {
     }
 
     // Remove the IDENTITY_INSERT Column from update
-    const updateSnippet = updateKeys.filter(key => !identityAttrs.includes(key))
+    const filteredUpdateClauses = updateKeys.filter(key => !identityAttrs.includes(key))
       .map(key => {
         const value = this.escape(updateValues[key]);
         key = this.quoteIdentifier(key);
         return `${targetTableAlias}.${key} = ${value}`;
-      }).join(', ');
+      });
+    const updateSnippet = filteredUpdateClauses.length > 0 ? `WHEN MATCHED THEN UPDATE SET ${filteredUpdateClauses.join(', ')}` : '';
 
     const insertSnippet = `(${insertKeysQuoted}) VALUES(${insertValuesEscaped})`;
+
     let query = `MERGE INTO ${tableNameQuoted} WITH(HOLDLOCK) AS ${targetTableAlias} USING (${sourceTableQuery}) AS ${sourceTableAlias}(${insertKeysQuoted}) ON ${joinCondition}`;
-    query += ` WHEN MATCHED THEN UPDATE SET ${updateSnippet} WHEN NOT MATCHED THEN INSERT ${insertSnippet} OUTPUT $action, INSERTED.*;`;
+    query += ` ${updateSnippet} WHEN NOT MATCHED THEN INSERT ${insertSnippet} OUTPUT $action, INSERTED.*;`;
     if (needIdentityInsertWrapper) {
       query = `SET IDENTITY_INSERT ${tableNameQuoted} ON; ${query} SET IDENTITY_INSERT ${tableNameQuoted} OFF;`;
     }
diff --git a/lib/dialects/mssql/query.js b/lib/dialects/mssql/query.js
index bbead007705a..f35c43d948e7 100644
--- a/lib/dialects/mssql/query.js
+++ b/lib/dialects/mssql/query.js
@@ -216,6 +216,11 @@ class Query extends AbstractQuery {
       return data;
     }
     if (this.isUpsertQuery()) {
+      // if this was an upsert and no data came back, that means the record exists, but the update was a noop.
+      // return the current instance and mark it as an "not an insert".
+      if (data && data.length === 0) {
+        return [this.instance || data, false];
+      }
       this.handleInsertQuery(data);
       return [this.instance || data, data[0].$action === 'INSERT'];
     }
diff --git a/lib/dialects/mysql/query-interface.js b/lib/dialects/mysql/query-interface.js
index bcdec9d2e5a7..4c7a43108e70 100644
--- a/lib/dialects/mysql/query-interface.js
+++ b/lib/dialects/mysql/query-interface.js
@@ -46,6 +46,7 @@ class MySQLQueryInterface extends QueryInterface {
 
     options.type = QueryTypes.UPSERT;
     options.updateOnDuplicate = Object.keys(updateValues);
+    options.upsertKeys = Object.values(options.model.primaryKeys).map(item => item.field);
 
     const model = options.model;
     const sql = this.queryGenerator.insertQuery(tableName, insertValues, model.rawAttributes, options);
diff --git a/lib/dialects/postgres/query.js b/lib/dialects/postgres/query.js
index 3640bda38648..8d63110340b2 100644
--- a/lib/dialects/postgres/query.js
+++ b/lib/dialects/postgres/query.js
@@ -267,7 +267,7 @@ class Query extends AbstractQuery {
       if (this.instance && this.instance.dataValues) {
         // If we are creating an instance, and we get no rows, the create failed but did not throw.
         // This probably means a conflict happened and was ignored, to avoid breaking a transaction.
-        if (this.isInsertQuery() && rowCount === 0) {
+        if (this.isInsertQuery() && !this.isUpsertQuery() && rowCount === 0) {
           throw new sequelizeErrors.EmptyResultError();
         }
 
diff --git a/lib/model.js b/lib/model.js
index 9960422d2383..16bfd90d697e 100644
--- a/lib/model.js
+++ b/lib/model.js
@@ -1672,7 +1672,7 @@ class Model {
    * @param  {object}                                                    [options.having] Having options
    * @param  {string}                                                    [options.searchPath=DEFAULT] An optional parameter to specify the schema search_path (Postgres only)
    * @param  {boolean|Error}                                             [options.rejectOnEmpty=false] Throws an error when no records found
-   * @param  {boolean}                                                   [options.dotNotation] Allows including tables having the same attribute/column names - which have a dot in them. 
+   * @param  {boolean}                                                   [options.dotNotation] Allows including tables having the same attribute/column names - which have a dot in them.
    *
    * @see
    * {@link Sequelize#query}
@@ -2438,7 +2438,7 @@ class Model {
    * @param  {object}       values                                        hash of values to upsert
    * @param  {object}       [options]                                     upsert options
    * @param  {boolean}      [options.validate=true]                       Run validations before the row is inserted
-   * @param  {Array}        [options.fields=Object.keys(this.attributes)] The fields to insert / update. Defaults to all changed fields
+   * @param  {Array}        [options.fields=Object.keys(this.attributes)] The fields to update if the record already exists. Defaults to all changed fields.  If none of the specified fields are present on the provided `values` object, an insert will still be attempted, but duplicate key conflicts will be ignored.
    * @param  {boolean}      [options.hooks=true]                          Run before / after upsert hooks?
    * @param  {boolean}      [options.returning=true]                      If true, fetches back auto generated values
    * @param  {Transaction}  [options.transaction]                         Transaction to run query under
@@ -3315,6 +3315,15 @@ class Model {
         }
         return f;
       });
+    } else if (fields && typeof fields === 'object') {
+      fields = Object.keys(fields).reduce((rawFields, f) => {
+        if (this.rawAttributes[f] && this.rawAttributes[f].field && this.rawAttributes[f].field !== f) {
+          rawFields[this.rawAttributes[f].field] = fields[f];
+        } else {
+          rawFields[f] = fields[f];
+        }
+        return rawFields;
+      }, {});
     }
 
     this._injectScope(options);
diff --git a/package.json b/package.json
index 383f7d52cd75..568a36837a37 100644
--- a/package.json
+++ b/package.json
@@ -185,7 +185,11 @@
       "@semantic-release/github"
     ],
     "branches": [
-      "v6"
+      "v6",
+      {
+        "name": "v6-alpha",
+        "prerelease": "alpha"
+      }
     ]
   },
   "publishConfig": {
diff --git a/test/integration/instance/increment.test.js b/test/integration/instance/increment.test.js
index ab1b15224823..d8345c25af9a 100644
--- a/test/integration/instance/increment.test.js
+++ b/test/integration/instance/increment.test.js
@@ -28,6 +28,7 @@ describe(Support.getTestDialectTeaser('Instance'), () => {
       touchedAt: { type: DataTypes.DATE, defaultValue: DataTypes.NOW },
       aNumber: { type: DataTypes.INTEGER },
       bNumber: { type: DataTypes.INTEGER },
+      cNumber: { type: DataTypes.INTEGER, field: 'CNumberColumn' },
       aDate: { type: DataTypes.DATE },
 
       validateTest: {
@@ -57,7 +58,7 @@ describe(Support.getTestDialectTeaser('Instance'), () => {
 
   describe('increment', () => {
     beforeEach(async function() {
-      await this.User.create({ id: 1, aNumber: 0, bNumber: 0 });
+      await this.User.create({ id: 1, aNumber: 0, bNumber: 0, cNumber: 0 });
     });
 
     if (current.dialect.supports.transactions) {
@@ -150,6 +151,27 @@ describe(Support.getTestDialectTeaser('Instance'), () => {
       expect(user3.bNumber).to.be.equal(2);
     });
 
+    it('single value should work when field name is different from database column name', async function() {
+      const user = await this.User.findByPk(1);
+      await user.increment('cNumber');
+      const user2 = await this.User.findByPk(1);
+      expect(user2.cNumber).to.be.equal(1);
+    });
+
+    it('array should work when field name is different from database column name', async function() {
+      const user = await this.User.findByPk(1);
+      await user.increment(['cNumber']);
+      const user2 = await this.User.findByPk(1);
+      expect(user2.cNumber).to.be.equal(1);
+    });
+
+    it('key value should work when field name is different from database column name', async function() {
+      const user = await this.User.findByPk(1);
+      await user.increment({ cNumber: 1 });
+      const user2 = await this.User.findByPk(1);
+      expect(user2.cNumber).to.be.equal(1);
+    });
+
     it('with timestamps set to true', async function() {
       const User = this.sequelize.define('IncrementUser', {
         aNumber: DataTypes.INTEGER
diff --git a/test/integration/model/upsert.test.js b/test/integration/model/upsert.test.js
index bfbab5e27e13..10001ce568ca 100644
--- a/test/integration/model/upsert.test.js
+++ b/test/integration/model/upsert.test.js
@@ -311,6 +311,30 @@ describe(Support.getTestDialectTeaser('Model'), () => {
         clock.restore();
       });
 
+      it('falls back to a noop if no update values are found in the upsert data', async function() {
+        const User = this.sequelize.define('user', {
+          username: DataTypes.STRING,
+          email: {
+            type: DataTypes.STRING,
+            field: 'email_address',
+            defaultValue: 'xxx@yyy.zzz'
+          }
+        }, {
+          // note, timestamps: false is important here because this test is attempting to see what happens
+          // if there are NO updatable fields (including timestamp values).
+          timestamps: false
+        });
+
+        await User.sync({ force: true });
+        // notice how the data does not actually have the update fields.
+        await User.upsert({ id: 42, username: 'jack' }, { fields: ['email'] });
+        await User.upsert({ id: 42, username: 'jill' }, { fields: ['email'] });
+        const user = await User.findByPk(42);
+        // just making sure the user exists, i.e. the insert happened.
+        expect(user).to.be.ok;
+        expect(user.username).to.equal('jack');  // second upsert should not have updated username.
+      });
+
       it('does not update using default values', async function() {
         await this.User.create({ id: 42, username: 'john', baz: 'new baz value' });
         const user0 = await this.User.findByPk(42);
diff --git a/types/lib/associations/belongs-to-many.d.ts b/types/lib/associations/belongs-to-many.d.ts
index c82e9294d971..b7106ffb197b 100644
--- a/types/lib/associations/belongs-to-many.d.ts
+++ b/types/lib/associations/belongs-to-many.d.ts
@@ -9,8 +9,7 @@ import {
   Model,
   ModelCtor,
   ModelType,
-  Transactionable,
-  WhereOptions,
+  Transactionable
 } from '../model';
 import { Association, AssociationScope, ForeignKeyOptions, ManyToManyOptions, MultiAssociationAccessors } from './base';
 
@@ -304,7 +303,7 @@ export interface BelongsToManyCreateAssociationMixinOptions extends CreateOption
  * @see Instance
  */
 export type BelongsToManyCreateAssociationMixin<TModel extends Model> = (
-  values?: Model['_creationAttributes'],
+  values?: TModel['_creationAttributes'],
   options?: BelongsToManyCreateAssociationMixinOptions
 ) => Promise<TModel>;
 
diff --git a/types/lib/associations/has-many.d.ts b/types/lib/associations/has-many.d.ts
index d98a96485af3..26b62444b13f 100644
--- a/types/lib/associations/has-many.d.ts
+++ b/types/lib/associations/has-many.d.ts
@@ -6,7 +6,7 @@ import {
   InstanceUpdateOptions,
   Model,
   ModelCtor,
-  Transactionable,
+  Transactionable
 } from '../model';
 import { Association, ManyToManyOptions, MultiAssociationAccessors } from './base';
 
@@ -210,7 +210,7 @@ export interface HasManyCreateAssociationMixinOptions extends CreateOptions<any>
  * @see Instance
  */
 export type HasManyCreateAssociationMixin<TModel extends Model> = (
-  values?: Model['_creationAttributes'],
+  values?: TModel['_creationAttributes'],
   options?: HasManyCreateAssociationMixinOptions
 ) => Promise<TModel>;
 
diff --git a/types/test/typescriptDocs/ModelInit.ts b/types/test/typescriptDocs/ModelInit.ts
index 163cb8ec88ee..a8848a0bc1cd 100644
--- a/types/test/typescriptDocs/ModelInit.ts
+++ b/types/test/typescriptDocs/ModelInit.ts
@@ -2,17 +2,9 @@
  * Keep this file in sync with the code in the "Usage" section in typescript.md
  */
 import {
-  Sequelize,
-  Model,
-  ModelDefined,
-  DataTypes,
-  HasManyGetAssociationsMixin,
-  HasManyAddAssociationMixin,
-  HasManyHasAssociationMixin,
-  Association,
-  HasManyCountAssociationsMixin,
-  HasManyCreateAssociationMixin,
-  Optional,
+  Association, DataTypes, HasManyAddAssociationMixin, HasManyCountAssociationsMixin,
+  HasManyCreateAssociationMixin, HasManyGetAssociationsMixin, HasManyHasAssociationMixin, Model,
+  ModelDefined, Optional, Sequelize
 } from "sequelize";
 
 const sequelize = new Sequelize("mysql://root:asd123@localhost:3306/mydb");
@@ -59,6 +51,7 @@ interface ProjectAttributes {
   id: number;
   ownerId: number;
   name: string;
+  description?: string;
 }
 
 interface ProjectCreationAttributes extends Optional<ProjectAttributes, "id"> {}
@@ -114,6 +107,10 @@ Project.init(
       type: new DataTypes.STRING(128),
       allowNull: false,
     },
+    description: {
+      type: new DataTypes.STRING(128),
+      allowNull: true,
+    },
   },
   {
     sequelize,
@@ -204,6 +201,7 @@ async function doStuffWithUser() {
 
   const project = await newUser.createProject({
     name: "first!",
+    ownerId: 123,
   });
 
   const ourUser = await User.findByPk(1, {