He worked for 5 years in the Severodonetsk Ministry of Internal Affairs of the Ministry of Internal Affairs in the Luhansk region, after...

First, contact the PFU branch at your place of residence with the problem or submit an electronic application on the PFU website: https://www.pfu.gov.ua/23131-elektronne-zvernennya-aplikatsijna-forma/.

Otherwise, if this information about seniority is not available due to the fault of the employer, then you can file a claim with the administrative court, stating that the employee is not responsible for the correctness of the employer's record keeping. After that, the court can oblige the Main Department of the Pension Fund of Ukraine to credit you with seniority.