How to reduce the size of a MSIX .Net Core 3.1 installation?

Chuck Bohling 346

I have a WPF/.Net Core 3.1 app that I'm packaging as an MSIX for submission to the Store. If I publish the app as a sideloading .msixbundle then install it, the resulting directory is WindowsApps is huge. I assume that's all of .Net Core. But most of the .dlls I don't use. I can delete them for the directory and the app runs fine. Is there a way to reduce the size of the installation?

As a test, I created a default WPF/Core 3.1 app and a MSIX packaging project. No additional code was added. I then built, published and installed the app. The WindowsApps directory contained 499 files and was 136MB. I briefly looked at dotnet /p:TrimUnusedDependencies but it really did't seem to help much.

So, any way to reduce the size of the installation?

Fay Wang - MSFT 5,221 Reputation points

2020-04-21T04:12:35.357+00:00

Currently, there is no direct method to reduce the size of the installation. Maybe you can put some resources from your app on your server and then download them after installation or use smaller images in your app.
Chuck Bohling 346 Reputation points

2020-04-29T02:00:01.987+00:00

Thanks for your answer. I understand the intention that an app comes self-contained but with potentially dozens of Core apps, a lot of disk space will be taken up by duplicate files.
Fay Wang - MSFT 5,221 Reputation points

2020-04-30T07:00:08.53+00:00

As I said, it's better not to put resource files in the app(e.g. video files, etc). You can put them from your app on your server and then download them after installation or use smaller images. In addition, I'm confused about your duplicate files, what are you specifically referring to?
Chuck Bohling 346 Reputation points

2020-04-30T18:13:35.413+00:00

When you publish a side-loading MSIX project then install it, the resulting directory in WindowsApps is like 135 MB. Most of the files are Core 3.1 .dll's. If other 3.1 apps do the same thing, they too will have 135 MB of 3.1 dll's. Most of the .dll's will be duplicates. That's correct right?
Fay Wang - MSFT 5,221 Reputation points

2020-05-04T09:37:56.847+00:00

I created .msixbundle and installed the app, after that I didn't find the Core 3.1 .dll in the WindowsApps directory, can you show us how you packaged your app as an MSIX? In addition, did you install the Core 3.1 SDK in your current environment?
Chuck Bohling 346 Reputation points

2020-05-11T20:22:33.473+00:00

I'm not sure if what gets installed is Core 3.1 or not. But what does get installed are a lot of dll's. For example:

api-ms-win-core-console-l1-1-0.dll

coreclr.dll

System.dll

SystemCore.dll

System.Threading.dll

Here's the full list: 8093-installedfiles.txt

I did a clean install of VS2019 and used .NET desktop and UWP workloads. Nothing else. I then created a default WPF C# project and a default MSIX project. Rebuilt and published a sideloading, release version. Then installed it. The app installation directory in WindowsApp has 291 entries, 13 of which are language directories. Total size was 136MB. This should be easy to repro. Is this correct? If so, every app that does the same thing I just did will have the same installation footprint, correct? Am I missing an option to prevent this? Is this just because it was sideloaded?
Fay Wang - MSFT 5,221 Reputation points

2020-05-14T08:43:07.697+00:00

Yeap, each package will contain these same dlls. Currently, did't find any method to prevent this.

1 answer

Lex Li (Microsoft) 5,847 Reputation points Microsoft Employee

2020-05-25T01:23:50.087+00:00

Starting from .NET Core 3.0 you can trim out what your app doesn't use,

https://learn.microsoft.com/en-us/dotnet/core/whats-new/dotnet-core-3-0#assembly-linking

However, that won't reduce too much from the final package as .NET Core WPF runtime is still large.

You might also consider generating a single file like that article talks about.
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