[Problem/Bug]: PDF Rendering loses online Images

What happened?

I'm using the WebView for PDF generation from HTML documents generated from Markdown Monster (an editor).

I'm noticing that the PDF engine is seemingly randomly not rendering online images.

This image shows rendered Html output which references online content. First is a static image, the second is a PlantUml Url. When I run the PDF image conversion (using Westwind.WebView library which in this case defers to the DevTools protocols PDF generation) the images may or may not show up. Local images appear to work fine, but online images randomly show or don't show.

The issue here is that beahavior is variable - sometimes all images show. Sometimes one or the other is missing and so on.

Importance

Important. My app's user experience is significantly compromised.

Runtime Channel

Stable release (WebView2 Runtime)

Runtime Version

150.0.4078.48

SDK Version

1.0.4022.49

Framework

WPF

Operating System

Windows 11

OS Version

10.0.26200

Repro steps

You can run the tests from here:

https://github.com/RickStrahl/Westwind.WebView/blob/master/Westwind.WebView.Test/HtmlToPdf/HtmlToPdfTests.cs

and point at a local Html document with online image links.

If you want a direct repro scenario:

• Download Markdown Monster
• Enter the text below.

Click the PDF button in the toolbar and run the PDF generation several times.

# Diagrama de Arquitectura: Contexto C4 (Nivel 1) — Alma

## Propósito

Mostrar a Alma como **un único sistema** con sus usuarios (estudiantes y operadores UPC) y los **sistemas externos** con los que interactúa. Audiencia: Sponsor UPC, Tekton Exec, Laureate Corporate, Enterprise Architect UPC.

![](https://weblog.west-wind.com/imageContent/2026/Getting-Inherited-Controller-Routes-to-work-and-ASP-NET-Core/Banner.jpg)

## Diagrama (PlantUML)

```plantuml
@startuml
!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Context.puml

title Diagrama de Contexto C4 - Alma (UPC / Laureate)

LAYOUT_LEFT_RIGHT()

Person(estudiante, "Estudiante UPC", "Usuario final del canal conversacional (WhatsApp + Web/Intranet)")
Person(operadores_upc, "Operadores y Administradores UPC", "Servicio al Estudiante, Marketing, DPO, Enterprise Architect")

System(alma, "Alma — Agente Conversacional UPC", "Atención conversacional + memoria a largo plazo + campañas proactivas WhatsApp")

System_Ext(upc_idam, "UPC SSO e Identidad", "OIDC para autenticar estudiantes y operadores")
System_Ext(upc_sor, "APIs de Registro UPC", "Notas, Matrícula, Pagos + bus de eventos académicos/financieros")
System_Ext(upc_ops, "Operaciones UPC", "Sistema de tickets + dashboards re-certificados")
System_Ext(whatsapp, "WhatsApp / Chattigo / Meta", "Gateway principal + adapter alternativo Twilio/360dialog (stub)")
System_Ext(ai_providers, "Proveedores IA", "Azure AI Foundry (LLM) + AWS Bedrock (embeddings) + Pinecone (vector)")

Rel_Right(estudiante, alma, "Conversa, recibe nudges, ejerce opt-out", "WhatsApp / Web")
Rel_Down(operadores_upc, alma, "Configura plantillas, recibe escalamientos, audita, gestiona consentimiento y borrado", "Panel Admin + Consola DPO")

Rel_Right(alma, upc_idam, "Autentica usuarios", "OIDC")
Rel_Right(alma, upc_sor, "Lee notas/matrícula/pagos vía MCP; consume eventos", "HTTPS / Webhook / Cola")
Rel_Down(alma, upc_ops, "Crea tickets de escalamiento + emite señales FCR/coste/salud", "API / Métricas")
Rel_Down(alma, whatsapp, "Inbound de estudiantes + outbound HSM aprobado", "HTTPS / Meta API")
Rel_Down(alma, ai_providers, "Inferencia LLM + embeddings + retrieval vectorial", "HTTPS")

Lay_Right(upc_sor, upc_ops)
Lay_Right(whatsapp, ai_providers)

SHOW_LEGEND()
@enduml

blah blah blah.

Repros in Edge Browser

No, issue does not reproduce in the corresponding Edge version

Regression

No, this never worked

Last working version (if regression)

No response

Start with Westwind.WebView.Test/HtmlToPdf/HtmlToPdfTests.cs and run the PDF tests against a local HTML document containing online image links. Compare repeated output with local images, and consider the issue resolved when referenced online images render consistently in generated PDFs.