WebReport error on ASP.NET Core host in ubuntu

This is code I used in my controller
FastReport.Web.WebReport Report = new FastReport.Web.WebReport();
Report.Report.Load($@"Reports/CashPurchaseItem.frx");
Report.Report.SetParameterValue("EmpName", EmpName);
Report.Report.SetParameterValue("Company", CompanyCode);
Report.Report.SetParameterValue("CustomerTo", CustomerName);
Report.Report.SetParameterValue("FromDT", DateFrom);
Report.Report.SetParameterValue("ToDT", DateTo);
Report.Report.SetParameterValue("ItemFrom", Item);
Report.Report.RegisterData(ds, "CashPurchaseItem");
ViewBag.WebReport = Report;

when I deploy web into ubuntu and access this url server return 502 Bad gateway when I comment this code block page render normally

FYI. I used FastReport.Web 2019 with ASP.NET Core 2.1

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