Resolving Missing Static Assets in the Native Blazor Report Viewer

Updated on Oct 14, 2026

Environment

Product	Progress® Telerik® Reporting
Report Viewer	Native Blazor Report Viewer
Version	20.2.26.1007

Description

On .NET 9 or later, an application that references Telerik.ReportViewer.BlazorNative version 20.2.26.1007 can fail to build with a missing static asset error. The diagnostic references a compressed output and a missing CSS source map, as in the following example:

text

The asset 'C:\Projects\BlazorApp\obj\Debug\net10.0\compressed\14jp1i84hx-{0}-2x8nbomfaf-2x8nbomfaf.gz' can not be found at any of the searched locations 'C:\Users\<user>\.nuget\packages\telerik.reportviewer.blazornative\20.2.26.1007\staticwebassets\css\reporting-blazor-viewer.css.map' and 'C:\Users\<user>\.nuget\packages\telerik.reportviewer.blazornative\20.2.26.1007\staticwebassets\css\reporting-blazor-viewer.css.map'.

The SDK may report the error from Microsoft.NET.Sdk.StaticWebAssets.Compression.targets. The missing input is reporting-blazor-viewer.css.map.

Separately, version 20.2.26.1007 lacks SVG export icons. The viewer displays missing icons, and requests to _content/Telerik.ReportViewer.BlazorNative/icons/export/, such as pdf.svg, return HTTP 404 responses. These missing SVGs do not cause build errors.

Cause

Version 20.2.26.1007 declares reporting-blazor-viewer.css.map as a static web asset but does not include the file.

.NET 9+ SDKs enable compression for static web assets by default, including source maps. This build step attempts to read the declared file and exposes the package mismatch.

Version 20.2.26.1007 does not declare the missing SVG files as package assets, so the SDK does not report an SVG build error. The viewer still requests the icons at runtime. The application must serve the SVG files at the expected URLs.

CSS Source Map Workarounds

The packaging issues will be fixed in the upcoming Telerik Reporting release. Until that release is available, apply one of the following temporary workarounds for the CSS source map. For missing SVG icons, apply the SVG icon workaround separately.

Workaround 1: Excluding the Source Map

This workaround removes the missing map from static web asset processing for the host application. It leaves the NuGet package cache unchanged.

1. Add the following item group directly inside the <Project> element of the application project file. Keep the existing package references and other settings unchanged:

   xml

   <ItemGroup>
     <StaticWebAsset Remove="$(NuGetPackageRoot)telerik.reportviewer.blazornative\20.2.26.1007\staticwebassets\css\reporting-blazor-viewer.css.map" />
     <StaticWebAssetEndpoint Remove="_content/Telerik.ReportViewer.BlazorNative/css/reporting-blazor-viewer.css*.map" />
   </ItemGroup>

2. Clean the application, rebuild it, and publish it again. Do not reuse previous build outputs for the first publish after this change.

In this case, the viewer CSS and JavaScript remain available. The map is not required for viewer functionality.

Workaround 2: Adding the Source Map

If you prefer to keep the asset, you can supply the source map file at the location that the package metadata expects. This workaround satisfies the existing asset declaration before the build processes static assets.

1. Download css/reporting-blazor-viewer.css.map from the NativeBlazorViewerAssets folder. Place the file at wwwroot/css/reporting-blazor-viewer.css.map in the application.

2. Add the following item group and target directly inside the <Project> element of the application project file:

   xml

   <ItemGroup>
     <None Include="wwwroot\css\reporting-blazor-viewer.css.map" />
   </ItemGroup>
   
   <Target Name="CopyReportingBlazorViewerCssMap" BeforeTargets="PreBuildEvent">
     <MakeDir Directories="$(NuGetPackageRoot)telerik.reportviewer.blazornative\20.2.26.1007\staticwebassets\css" />
     <Copy
       SourceFiles="$(MSBuildProjectDirectory)\wwwroot\css\reporting-blazor-viewer.css.map"
       DestinationFolder="$(NuGetPackageRoot)telerik.reportviewer.blazornative\20.2.26.1007\staticwebassets\css"
       SkipUnchangedFiles="true" />
   </Target>

   The target uses NuGetPackageRoot rather than a hard-coded user profile. Ensure the build account can write to that directory.

3. Clean the application and rebuild it.

The source map now exists at the path that the package declares.

SVG Icon Workaround

Keep replacement SVGs in the application rather than the shared NuGet cache. The application serves its own files at the URLs that the viewer expects. No project-file changes are required for the icons in version 20.2.26.1007.

To restore the export icons:

1. Download the icons folder from the NativeBlazorViewerAssets folder.

2. Copy that folder to wwwroot/_content/Telerik.ReportViewer.BlazorNative/icons in the application. Preserve the export subfolder and the SVG file names. The resulting structure is:

   text

   wwwroot/
   	_content/
   		Telerik.ReportViewer.BlazorNative/
   			icons/
   				export/
   					csv.svg
   					docx.svg
   					image.svg
   					options.svg
   					pdf.svg
   					pptx.svg
   					rtf.svg
   					xlsx.svg

3. Clean the application and rebuild.