HTML-to-PDF Proxy Authentication Errors from Remote Assets

The HTML arrives as a string. PDF generation starts, then a network exception mentions proxy authentication. Look inside the document before blaming the PDF file.

A renderer can resolve resources referenced by its input. A remote image, stylesheet, font or supported import introduces another request. Which resource types are supported depends on the renderer; supplying the main markup does not guarantee an entirely offline conversion.

Locate the second URL

Record the resource the renderer was retrieving when it failed. Resolve relative references against the actual base URL. An innocent-looking logo path can point outside the application when that base differs from the one used in a browser preview.

Then identify the downloader. A successful request made by your own HTTP client does not configure a renderer's internal resource retrieval. Use the renderer's documented resource interface or an approved prefetching arrangement if it provides one.

Credentials for the source application are also not automatically proxy credentials. The renderer may run under a service identity with another environment and another network path.

Make the dependency explicit

For reports intended to work offline, supply approved local or embedded resources through the supported mechanism. If remote resources are required, make their permitted destinations, authentication and failure behavior part of the rendering design.

A missing logo and a failed conversion are different possible outcomes. Check how the library handles retrieval errors instead of declaring the report complete merely because a PDF file was created. Keep the failed resource and request stage in the diagnostic; repeatedly changing the original document's URL can leave the actual download untouched.