diff --git a/gravitee-apim-rest-api/gravitee-apim-rest-api-service/src/main/java/io/gravitee/apim/core/group/domain_service/ValidateGroupsDomainService.java b/gravitee-apim-rest-api/gravitee-apim-rest-api-service/src/main/java/io/gravitee/apim/core/group/domain_service/ValidateGroupsDomainService.java
index bec8024499f..765fa073ea3 100644
--- a/gravitee-apim-rest-api/gravitee-apim-rest-api-service/src/main/java/io/gravitee/apim/core/group/domain_service/ValidateGroupsDomainService.java
+++ b/gravitee-apim-rest-api/gravitee-apim-rest-api-service/src/main/java/io/gravitee/apim/core/group/domain_service/ValidateGroupsDomainService.java
@@ -21,12 +21,14 @@
 import io.gravitee.apim.core.DomainService;
 import io.gravitee.apim.core.group.model.Group;
 import io.gravitee.apim.core.group.query_service.GroupQueryService;
+import io.gravitee.apim.core.utils.StringUtils;
 import io.gravitee.apim.core.validation.Validator;
 import io.gravitee.definition.model.DefinitionVersion;
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.function.Function;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
@@ -66,12 +68,21 @@ public Result<Input> validateAndSanitize(Input input) {
 
         var errors = new ArrayList<Error>();
 
+        var noPrimaryOwnerResultFromIds = validateAndSanitizeNoPrimaryOwners(groupsFromIds, Group::getId);
+        var noPrimaryOwnerResultFromNames = validateAndSanitizeNoPrimaryOwners(groupsFromNames, Group::getName);
+
+        noPrimaryOwnerResultFromIds.errors().ifPresent(errors::addAll);
+        noPrimaryOwnerResultFromNames.errors().ifPresent(errors::addAll);
+
+        var sanitizedFromIds = noPrimaryOwnerResultFromIds.value().orElse(List.of());
+        var sanitizedFromNames = noPrimaryOwnerResultFromNames.value().orElse(List.of());
+
         if (DefinitionVersion.V2.getLabel().equals(input.definitionVersion)) {
-            sanitizedGroups.addAll(groupsFromIds.stream().map(Group::getName).toList());
-            sanitizedGroups.addAll(groupsFromNames.stream().map(Group::getName).toList());
+            sanitizedGroups.addAll(sanitizedFromIds.stream().map(Group::getName).toList());
+            sanitizedGroups.addAll(sanitizedFromNames.stream().map(Group::getName).toList());
         } else {
-            sanitizedGroups.addAll(groupsFromIds.stream().map(Group::getId).toList());
-            sanitizedGroups.addAll(groupsFromNames.stream().map(Group::getId).toList());
+            sanitizedGroups.addAll(sanitizedFromIds.stream().map(Group::getId).toList());
+            sanitizedGroups.addAll(sanitizedFromNames.stream().map(Group::getId).toList());
         }
 
         givenGroups.removeAll(groupIds);
@@ -83,4 +94,25 @@ public Result<Input> validateAndSanitize(Input input) {
 
         return Result.ofBoth(input.sanitized(sanitizedGroups), errors);
     }
+
+    private Result<List<Group>> validateAndSanitizeNoPrimaryOwners(List<Group> groups, Function<Group, String> idMapper) {
+        var sanitized = new ArrayList<>(groups);
+        var groupsWithPrimaryOwner = sanitized.stream().filter(group -> StringUtils.isNotEmpty(group.getApiPrimaryOwner())).toList();
+        sanitized.removeAll(groupsWithPrimaryOwner);
+        var errors = buildPrimaryOwnerErrors(groupsWithPrimaryOwner, idMapper);
+        return Result.ofBoth(sanitized, errors);
+    }
+
+    private List<Error> buildPrimaryOwnerErrors(List<Group> groupsWithPrimaryOwner, Function<Group, String> idMapper) {
+        return groupsWithPrimaryOwner
+            .stream()
+            .map(idMapper)
+            .map(id ->
+                Error.warning(
+                    "Group [%s] will be discarded because it contains an API Primary Owner member, which is not supported with by the operator.",
+                    id
+                )
+            )
+            .toList();
+    }
 }
diff --git a/gravitee-apim-rest-api/gravitee-apim-rest-api-service/src/test/java/io/gravitee/apim/core/group/domain_service/ValidateGroupsDomainServiceTest.java b/gravitee-apim-rest-api/gravitee-apim-rest-api-service/src/test/java/io/gravitee/apim/core/group/domain_service/ValidateGroupsDomainServiceTest.java
new file mode 100644
index 00000000000..eec3a4fb732
--- /dev/null
+++ b/gravitee-apim-rest-api/gravitee-apim-rest-api-service/src/test/java/io/gravitee/apim/core/group/domain_service/ValidateGroupsDomainServiceTest.java
@@ -0,0 +1,101 @@
+/*
+ * Copyright © 2015 The Gravitee team (http://gravitee.io)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.gravitee.apim.core.group.domain_service;
+
+import inmemory.GroupQueryServiceInMemory;
+import io.gravitee.apim.core.group.model.Group;
+import io.gravitee.apim.core.validation.Validator;
+import io.gravitee.definition.model.DefinitionVersion;
+import java.util.List;
+import java.util.Set;
+import org.assertj.core.api.SoftAssertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayNameGeneration;
+import org.junit.jupiter.api.DisplayNameGenerator;
+import org.junit.jupiter.api.Test;
+
+/**
+ * @author Antoine CORDIER (antoine.cordier at graviteesource.com)
+ * @author GraviteeSource Team
+ */
+@DisplayNameGeneration(DisplayNameGenerator.ReplaceUnderscores.class)
+class ValidateGroupsDomainServiceTest {
+
+    private static final String ENVIRONMENT = "TEST";
+
+    private final GroupQueryServiceInMemory groupQueryService = new GroupQueryServiceInMemory();
+
+    private ValidateGroupsDomainService validateGroupsDomainService;
+
+    @BeforeEach
+    void setUp() {
+        groupQueryService.initWith(
+            List.of(
+                Group.builder().environmentId(ENVIRONMENT).id("group-with-po-id").name("group-with-po").apiPrimaryOwner("some-po").build(),
+                Group.builder().environmentId(ENVIRONMENT).id("group-without-po-id").name("group-without-po").build()
+            )
+        );
+        validateGroupsDomainService = new ValidateGroupsDomainService(groupQueryService);
+    }
+
+    @Test
+    void should_return_warnings_with_group_with_primary_owner_and_sanitize_v2() {
+        var givenGroups = Set.of("group-with-po-id", "group-without-po");
+
+        var input = new ValidateGroupsDomainService.Input(ENVIRONMENT, givenGroups, DefinitionVersion.V2.getLabel());
+
+        var result = validateGroupsDomainService.validateAndSanitize(input);
+
+        SoftAssertions.assertSoftly(soft -> {
+            soft.assertThat(result.value()).isNotEmpty();
+            soft.assertThat(result.value()).hasValue(input.sanitized(Set.of("group-without-po")));
+            soft.assertThat(result.errors()).isNotEmpty();
+            soft
+                .assertThat(result.errors())
+                .hasValue(
+                    List.of(
+                        Validator.Error.warning(
+                            "Group [group-with-po-id] will be discarded because it contains an API Primary Owner member, which is not supported with by the operator."
+                        )
+                    )
+                );
+        });
+    }
+
+    @Test
+    void should_return_warnings_with_group_with_primary_owner_and_sanitize_v4() {
+        var givenGroups = Set.of("group-with-po", "group-without-po-id");
+
+        var input = new ValidateGroupsDomainService.Input(ENVIRONMENT, givenGroups, DefinitionVersion.V4.getLabel());
+
+        var result = validateGroupsDomainService.validateAndSanitize(input);
+
+        SoftAssertions.assertSoftly(soft -> {
+            soft.assertThat(result.value()).isNotEmpty();
+            soft.assertThat(result.value()).hasValue(input.sanitized(Set.of("group-without-po-id")));
+            soft.assertThat(result.errors()).isNotEmpty();
+            soft
+                .assertThat(result.errors())
+                .hasValue(
+                    List.of(
+                        Validator.Error.warning(
+                            "Group [group-with-po] will be discarded because it contains an API Primary Owner member, which is not supported with by the operator."
+                        )
+                    )
+                );
+        });
+    }
+}