Bootstrap Blazor Script Not Generated in Docker

[rabauss]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I'm facing an issue with my application using Bootstrap Blazor version 9.7.4. When running in a Docker container, the script <script src="@Assets["_content/BootstrapBlazor/js/bootstrap.blazor.bundle.min.js"]"></script> fails to load, resulting in a 500 Internal Server Error. In v9.7.3 everything is still working fine!

• Environment:

  • .NET Version: mcr.microsoft.com/dotnet/aspnet:9.0
  • Bootstrap Blazor Version: 9.7.4

• Issue:

  • The script is not generated in Docker, but it works fine locally.
  • Produces a 500 error in the browser console during script load.

Any guidance on resolving this would be greatly appreciated.
Thank you!

Expected Behavior

Script should load without errors in Docker as it does locally.

Interactive render mode

Interactive Server (Interactive server-side rendering (interactive SSR) using Blazor Server)

Steps To Reproduce

Steps to reproduce involve building and running the application in a Docker container, then observing the error upon accessing the application.

Exceptions (if any)

No response

.NET Version

NET9.0

Anything else?

No response

[bb-auto[bot]]

@rabauss Thank you for filing this issue. In order for us to investigate this issue, please provide a minimalistic repro project that illustrates the problem.

[ArgoZhang]

@rabauss hi. thank you for report this issue. could you try this https://github.com/dotnetcore/BootstrapBlazor/blob/main/src/BootstrapBlazor.Server/Dockerfile

later i will double check it

[rabauss]

I almost have similar dockerfile - and it's working fine with v9.7.3

# Base image
FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/aspnet:9.0 AS base
WORKDIR /app
EXPOSE 8080 8081

RUN apt-get update && apt-get install -y curl

# Set environment variables
ENV ASPNETCORE_FORWARDEDHEADERS_ENABLED=true \
    DOTNET_SYSTEM_GLOBALIZATION_INVARIANT=false \
    LC_ALL=de_DE.UTF-8 \
    LANG=de_DE.UTF-8

# Build image
FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:9.0 AS build
WORKDIR /src
COPY ["Intranet.sln", "./"]
COPY ["Directory.Packages.props", "./"]
COPY ["Intranet.Application/Intranet.Application.csproj", "Intranet.Application/"]
COPY ["Intranet.Command/Intranet.Command.csproj", "Intranet.Command/"]
COPY ["Intranet.Domain/Intranet.Domain.csproj", "Intranet.Domain/"]
COPY ["Intranet.Infrastructure/Intranet.Infrastructure.csproj", "Intranet.Infrastructure/"]
COPY ["Intranet.WebUI.Server/Intranet.WebUI.Server.csproj", "Intranet.WebUI.Server/"]
COPY ["Intranet.WebUI.Client/Intranet.WebUI.Client.csproj", "Intranet.WebUI.Client/"]

# Restore dependencies
RUN dotnet restore "./Intranet.sln"

# Copy source code
COPY . .

# Build the project
RUN dotnet build "./Intranet.sln" -c Release -o /app/build

# Publish stage
FROM build AS publish
RUN dotnet publish "./Intranet.sln" -c Release -o /app/publish /p:UseAppHost=false

# Final image
FROM base AS final
WORKDIR /app

# Create a new user and use it
RUN useradd -ms /bin/bash appuser
RUN chown -R appuser:appuser /app
USER appuser

COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "Intranet.WebUI.Server.dll"]

[rabauss]

I just wonder how I could log more errors with serilog.
Maybe you could tell me to get some debug log from the docker container?
Currently, I just get the following log:

2025-06-29 12:18:51.414 +00:00 [ERR] An unhandled exception has occurred while executing the request.
System.ArgumentOutOfRangeException:  (Parameter 'count')
Actual value was 207857.
   at Microsoft.AspNetCore.Http.SendFileFallback.SendFileAsync(Stream destination, String filePath, Int64 offset, Nullable`1 count, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Http.SendFileResponseExtensions.SendFileAsyncCore(HttpResponse response, String fileName, Int64 offset, Nullable`1 count, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Http.SendFileResponseExtensions.SendFileAsyncCore(HttpResponse response, IFileInfo file, Int64 offset, Nullable`1 count, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.StaticAssets.StaticAssetsInvoker.SendAsync(StaticAssetInvocationContext context)
   at Microsoft.AspNetCore.StaticAssets.StaticAssetsInvoker.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddlewareImpl.<Invoke>g__Awaited|10_0(ExceptionHandlerMiddlewareImpl middleware, HttpContext context, Task task)

[ArgoZhang]

@rabauss hi. thanks for you feedback. could you post a address for docker image? i will take a look

[rabauss]

I'm sorry it's a private image for an internal project which I cannot share!

[ArgoZhang]

@rabauss so. could you make a demo repro docker image? I want to help you solve this problem

[rabauss]

@ArgoZhang I created a small demo project with which the problem is reproducable - see: https://github.com/rabauss/Intranet.Test
If you start the container with docker compose up the JS is not loadable (error 500).
Running the solution with Visual Studio, then the JS is running.

[ArgoZhang]

@rabauss hi i got something. please update the following changes

<script src="@Assets["_content/BootstrapBlazor/js/bootstrap.blazor.bundle.min.js"]"></script>

update to

<script src="_content/BootstrapBlazor/js/bootstrap.blazor.bundle.min.js"></script>
<script src="_framework/blazor.web.js"></script>

[rabauss]

Thanks for the working solution 🚀!
I just wonder why it was working with v9.7.3 🤔
Are changes in the JS files without the assets helper recognized by the browser?

[ArgoZhang]

@rabauss I just did a test and got the same error on 9.7.3, which is in line with my expectations

[rabauss]

Oh, sorry, I was wrong - my current live system is running 9.7.0 and also with the asset helper.
But for now, I'm fine with running it without the asset helper, as long as the browser still detects JS changes - not tested yet