diff --git a/src/Squidex.Domain.Apps.Entities/Schemas/Guards/GuardSchema.cs b/src/Squidex.Domain.Apps.Entities/Schemas/Guards/GuardSchema.cs
index c95bac2f6..fb59048a1 100644
--- a/src/Squidex.Domain.Apps.Entities/Schemas/Guards/GuardSchema.cs
+++ b/src/Squidex.Domain.Apps.Entities/Schemas/Guards/GuardSchema.cs
@@ -82,7 +82,7 @@ namespace Squidex.Domain.Apps.Entities.Schemas.Guards
                     error(new ValidationError("Field ids is required.", nameof(command.FieldIds)));
                 }
 
-                if (command.FieldIds.Count != schema.Fields.Count || command.FieldIds.Any(x => !schema.FieldsById.ContainsKey(x)))
+                if (command.FieldIds != null && (command.FieldIds.Count != schema.Fields.Count || command.FieldIds.Any(x => !schema.FieldsById.ContainsKey(x))))
                 {
                     error(new ValidationError("Ids must cover all fields.", nameof(command.FieldIds)));
                 }
diff --git a/tests/Squidex.Domain.Apps.Entities.Tests/Schemas/Guards/GuardSchemaFieldTests.cs b/tests/Squidex.Domain.Apps.Entities.Tests/Schemas/Guards/GuardSchemaFieldTests.cs
index 3d121e8ab..7636f0faa 100644
--- a/tests/Squidex.Domain.Apps.Entities.Tests/Schemas/Guards/GuardSchemaFieldTests.cs
+++ b/tests/Squidex.Domain.Apps.Entities.Tests/Schemas/Guards/GuardSchemaFieldTests.cs
@@ -203,6 +203,22 @@ namespace Squidex.Domain.Apps.Entities.Schemas.Guards
             GuardSchemaField.CanUpdate(schema_0, command);
         }
 
+        [Fact]
+        public void CanUpdate_should_throw_exception_if_properties_null()
+        {
+            var command = new UpdateField { FieldId = 2, Properties = null };
+
+            Assert.Throws<ValidationException>(() => GuardSchemaField.CanUpdate(schema_0, command));
+        }
+
+        [Fact]
+        public void CanUpdate_should_throw_exception_if_properties_not_valid()
+        {
+            var command = new UpdateField { FieldId = 2, Properties = new StringFieldProperties { MinLength = 10, MaxLength = 5 } };
+
+            Assert.Throws<ValidationException>(() => GuardSchemaField.CanUpdate(schema_0, command));
+        }
+
         [Fact]
         public void CanAdd_should_throw_exception_if_field_already_exists()
         {
@@ -227,6 +243,14 @@ namespace Squidex.Domain.Apps.Entities.Schemas.Guards
             Assert.Throws<ValidationException>(() => GuardSchemaField.CanAdd(schema_0, command));
         }
 
+        [Fact]
+        public void CanAdd_should_throw_exception_if_properties_null()
+        {
+            var command = new AddField { Name = "field3", Properties = null };
+
+            Assert.Throws<ValidationException>(() => GuardSchemaField.CanAdd(schema_0, command));
+        }
+
         [Fact]
         public void CanAdd_should_throw_exception_if_partitioning_not_valid()
         {
diff --git a/tests/Squidex.Domain.Apps.Entities.Tests/Schemas/Guards/GuardSchemaTests.cs b/tests/Squidex.Domain.Apps.Entities.Tests/Schemas/Guards/GuardSchemaTests.cs
index 407b72608..1f2bd3233 100644
--- a/tests/Squidex.Domain.Apps.Entities.Tests/Schemas/Guards/GuardSchemaTests.cs
+++ b/tests/Squidex.Domain.Apps.Entities.Tests/Schemas/Guards/GuardSchemaTests.cs
@@ -170,6 +170,15 @@ namespace Squidex.Domain.Apps.Entities.Schemas.Guards
         }
 
         [Fact]
+        public void CanReorder_should_throw_exception_if_field_ids_null()
+        {
+            var command = new ReorderFields { FieldIds = null };
+
+            Assert.Throws<ValidationException>(() => GuardSchema.CanReorder(schema_0, command));
+        }
+
+        [Fact]
+
         public void CanReorder_should_not_throw_exception_if_field_ids_are_valid()
         {
             var command = new ReorderFields { FieldIds = new List<long> { 1, 2 } };