Merge pull request #9193 from terraform-providers/b-aws_db_instance-a…

…llow_major_version_update-modify

resource/aws_db_instance: Prevent InvalidParameterCombination: No modifications were requested error when updating only allow_major_version_upgrade argument

aws/resource_aws_db_instance.go

@@ -1470,7 +1470,8 @@ func resourceAwsDbInstanceUpdate(d *schema.ResourceData, meta interface{}) error
 	if d.HasChange("allow_major_version_upgrade") {
 		d.SetPartial("allow_major_version_upgrade")
 		req.AllowMajorVersionUpgrade = aws.Bool(d.Get("allow_major_version_upgrade").(bool))
-		requestUpdate = true
+		// Having allowing_major_version_upgrade by itself should not trigger ModifyDBInstance
+		// as it results in InvalidParameterCombination: No modifications were requested
 	}
 	if d.HasChange("backup_retention_period") {
 		d.SetPartial("backup_retention_period")

aws/resource_aws_db_instance_test.go

@@ -293,6 +293,13 @@ func TestAccAWSDBInstance_AllowMajorVersionUpgrade(t *testing.T) {
 					"skip_final_snapshot",
 				},
 			},
+			{
+				Config: testAccAWSDBInstanceConfigAllowMajorVersionUpgrade(rName, false),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSDBInstanceExists(resourceName, &dbInstance1),
+					resource.TestCheckResourceAttr(resourceName, "allow_major_version_upgrade", "false"),
+				),
+			},
 		},
 	})
 }