Unable to download custom SSSP app (size & cert OK)

Smart TV Smart Signage and Hospitality
1

Hi everyone,

I’m trying to sideload a custom web-app onto a 2022 series Samsung Smart Signage display (SSSP).
After I enter the URL in App Management → Installa applicazione personalizzata, the progress bar never appears and the TV shows the generic banner:

“Impossibile scaricare l’applicazione” / “Unable to download the app”

1 Folder structure on the web-server

/app/sssp/
├── sssp_config.xml
└── signage.wgt    (signed with Samsung distributor cert – same DUID as the panel)

2 Current sssp_config.xml

<?xml version="1.0" encoding="UTF-8"?>
<widget>
    <widgetname>signage.wgt</widgetname>
    <size>14563</size>
    <ver>1.0.0</ver>
    <auto_launch>true</auto_launch>
</widget>
  • 14563 bytes is the exact Content-Length returned by IIS (see curl output below).
  • The file name and case match the real file on disk.
  • I bumped <ver> each time I rebuilt.