Reportviewer 2015 =link= -
(Microsoft.ReportViewer.Runtime version 12.0) is a unique beast. It arrived during the transition from traditional MSI installers to NuGet packages, and it supports both Local Mode (RDLC files) and Remote Mode (SSRS 2008–2016).
byte[] pdfBytes = report.Render( format: "PDF", deviceInfo: null, mimeType: out mimeType, encoding: out encoding, fileNameExtension: out fileNameExtension, streams: out streams, warnings: out warnings ); reportviewer 2015
If you are stuck migrating from ReportViewer 2010 or 2012, the 2015 version is your safest upgrade path. (Microsoft