diff --git a/addons/web/static/src/js/views/basic/basic_model.js b/addons/web/static/src/js/views/basic/basic_model.js
index b8211b2f048..1e14b4c1f41 100644
--- a/addons/web/static/src/js/views/basic/basic_model.js
+++ b/addons/web/static/src/js/views/basic/basic_model.js
@@ -3253,7 +3253,7 @@ var BasicModel = AbstractModel.extend({
             var type = record.fields[fieldName].type;
             var value;
             if (type === 'one2many' || type === 'many2many') {
-                if (commands[fieldName] && commands[fieldName].length) { // replace localId by commands
+                if (!options.changesOnly || (commands[fieldName] && commands[fieldName].length)) { // replace localId by commands
                     changes[fieldName] = commands[fieldName];
                 } else { // no command -> no change for that field
                     delete changes[fieldName];
@@ -3424,12 +3424,12 @@ var BasicModel = AbstractModel.extend({
                                 commands[fieldName].push(x2ManyCommands.link_to(list.res_ids[i]));
                                 continue;
                             }
-                            changes = this._generateChanges(relRecord, _.extend({}, options, {changesOnly: true}));
+                            changes = this._generateChanges(relRecord, options);
                             if (!this.isNew(relRecord.id)) {
                                 // the subrecord already exists in db
                                 commands[fieldName].push(x2ManyCommands.link_to(relRecord.res_id));
-                                delete changes.id;
-                                if (!_.isEmpty(changes)) {
+                                if (this.isDirty(relRecord.id)) {
+                                    delete changes.id;
                                     commands[fieldName].push(x2ManyCommands.update(relRecord.res_id, changes));
                                 }
                             } else {
diff --git a/addons/web/static/tests/fields/relational_fields/field_one2many_tests.js b/addons/web/static/tests/fields/relational_fields/field_one2many_tests.js
index f3424f18502..7565f6ff41a 100644
--- a/addons/web/static/tests/fields/relational_fields/field_one2many_tests.js
+++ b/addons/web/static/tests/fields/relational_fields/field_one2many_tests.js
@@ -9687,6 +9687,82 @@ QUnit.module('fields', {}, function () {
             form.destroy();
             testUtils.unpatch(FieldOne2Many);
         });
+
+        QUnit.test('nested one2many, onchange, no command value', async function (assert) {
+            // This test ensures that we always send all values to onchange rpcs for nested
+            // one2manys, even if some field hasn't changed. In this particular test case,
+            // a first onchange returns a value for the inner one2many, and a second onchange
+            // removes it, thus restoring the field to its initial empty value. From this point,
+            // the nested one2many value must still be sent to onchange rpcs (on the main record),
+            // as it might be used to compute other fields (so the fact that the nested o2m is empty
+            // must be explicit).
+            assert.expect(3);
+
+            this.data.turtle.fields.o2m = {
+                string: "o2m", type: "one2many", relation: 'partner', relation_field: 'trululu',
+            };
+            this.data.turtle.fields.turtle_bar.default = true;
+            this.data.partner.onchanges.turtles = function (obj) {};
+            this.data.turtle.onchanges.turtle_bar = function (obj) {
+                if (obj.turtle_bar) {
+                    obj.o2m = [[5], [0, false, { display_name: "default" }]];
+                } else {
+                    obj.o2m = [[5]];
+                }
+            };
+
+            let step = 1;
+            const form = await createView({
+                View: FormView,
+                model: 'partner',
+                data: this.data,
+                arch: `<form>
+                        <field name="turtles">
+                            <tree editable="bottom">
+                                <field name="o2m"/>
+                                <field name="turtle_bar"/>
+                            </tree>
+                        </field>
+                    </form>`,
+                async mockRPC(route, args) {
+                    if (step === 3 && args.method === 'onchange' && args.model === 'partner') {
+                        assert.deepEqual(args.args[1].turtles[0][2], {
+                            turtle_bar: false,
+                            o2m: [], // we must send a value for this field
+                        });
+                    }
+                    const result = await this._super(...arguments);
+                    if (args.model === 'turtle') {
+                        // sanity checks; this is what the onchanges on turtle must return
+                        if (step === 2) {
+                            assert.deepEqual(result.value, {
+                                o2m: [[5], [0, false, { display_name: "default" }]],
+                                turtle_bar: true,
+                            });
+                        }
+                        if (step === 3) {
+                            assert.deepEqual(result.value, {
+                                o2m: [[5]],
+                            });
+                        }
+                    }
+                    return result;
+                },
+            });
+
+            step = 2;
+            await testUtils.dom.click(form.$('.o_field_x2many_list .o_field_x2many_list_row_add a'));
+            // use of owlCompatibilityExtraNextTick because we have an x2many field with a boolean field
+            // (written in owl), so when we add a line, we sequentially render the list itself
+            // (including the boolean field), so we have to wait for the next animation frame, and
+            // then we render the control panel (also in owl), so we have to wait again for the
+            // next animation frame
+            await testUtils.owlCompatibilityExtraNextTick();
+            step = 3;
+            await testUtils.dom.click(form.$('.o_data_row .o_field_boolean input'));
+
+            form.destroy();
+        });
     });
 });
 });
diff --git a/addons/web/static/tests/views/basic_model_tests.js b/addons/web/static/tests/views/basic_model_tests.js
index dd802790210..a97fb0ddd1c 100644
--- a/addons/web/static/tests/views/basic_model_tests.js
+++ b/addons/web/static/tests/views/basic_model_tests.js
@@ -1145,7 +1145,7 @@ odoo.define('web.basic_model_tests', function (require) {
                 mockRPC: function (route, args) {
                     if (args.method === 'create') {
                         // has to be done before the call to _super
-                        assert.notOk('product_ids' in args.args[0], "should not have any value");
+                        assert.deepEqual(args.args[0].product_ids, [], "should not have any command");
                         assert.notOk('category' in args.args[0], "should not have other fields");
 
                         assert.strictEqual(args.kwargs.context.active_field, 2,