Fatal error: Uncaught Error: Interface "Illuminate\Contracts\Validation\ValidationRule" not found in /home/nikitin/vivoback.nixtio.com/app/Rules/QuestionAnswerExistsRule.php:8 Stack trace: #0 {main} thrown in /home/nikitin/vivoback.nixtio.com/app/Rules/QuestionAnswerExistsRule.php on line 8