This documentation addresses common errors encountered when using Aspose.Words for document conversion (e.g., to PDF, JPEG, PNG) in a .NET Core 2.0 application running inside a Docker container. The errors typically relate to SkiaSharp type initializers and occur only in Docker environments (not in local IIS Express).
1. PDF Conversion Error
The type initializer for ‘SkiaSharp.SKManagedStream’ threw an exception.
2. JPEG/PNG Conversion Error
The type initializer for ‘SkiaSharp.SKImageInfo’ threw an exception.
1. Install Required Dependencies in Docker
Add the necessary native libraries to your Docker image. These include:
- libgdiplus (for graphics operations)
- libfontconfig1 (for font rendering)
- libc6-dev (C library utilities)
Update your Dockerfile to include these dependencies:
# Use a .NET Core 2.0 compatible base image
FROM mcr.microsoft.com/dotnet/core/sdk:2.1 AS build-env
&& rm -rf /var/lib/apt/lists/*
# Rest of your Dockerfile (build steps, entrypoint, etc.)
2. Include SkiaSharp Native Assets
Ensure the SkiaSharp.NativeAssets.Linux NuGet package is installed in your project. This package provides Linux-specific binaries required for SkiaSharp to work in Docker.
dotnet add package SkiaSharp.NativeAssets.Linux –version 2.88.0
Note: Use a version compatible with your project and Aspose.Words.
4. Update Aspose.Words and SkiaSharp
Ensure you’re using the latest compatible versions of:
- Aspose.Words
- SkiaSharp
- SkiaSharp.NativeAssets.Linux
Check for version conflicts in your .csproj file.
5. Font Configuration
If fonts are missing (common in headless Docker environments), explicitly install fonts or copy them to the container:
# Example: Install DejaVu fonts
RUN apt-get install -y ttf-dejavu
6. Test in Debug Mode
Run the Docker container in debug mode to capture detailed error logs:
docker run -it –rm your-image-name
