Save custom annotation as blob PDF file to server in ASP MVC or using JS

[Mohammed Zaki]

hello,
in our app, we have custom annotation (barcode) as a stamp, anyway, I generate it in runtime, and its showing in the viewer, however when I try to download the file, it showing it as a draft. that's the first issue,
the second issue when I try to save it using this guide (link below)
https://www.pdftron.com/documentation/web/guides/annotations/saving-loading-annotations/
i get Cannot read property 'exportAnnotations' of null
which came from var xfdfString = annotManager.exportAnnotations();