I used https://docs.telerik.com/reporting/html5-report-viewer-howto-use-it-with-reportserver to setup an HTML5 Report Viewer with Report Server. After running the project, the viewer does not load. It seems that it could not find telerikReportViewer script.
Workaround: Instead of
<script src="/api/reports/resources/js/telerikReportViewer"></script>
use absolute path:<script src="http://yourreportserverhost:83/api/reports/resources/js/telerikReportViewer"></script>