ReactiveUI v8.0.0 released

Tuesday, May 1, 2018
Release Notes
Geoffrey Huntley

Hello ;-)

We never want to do a release this big ever again. A lot of time and effort went into this release from dedicated folks in the community.

One of the biggest factors in this release was that Microsoft changed their toolchain three times over and ReactiveUI was in the centre of that change. Dear Microsoft, never again please. We're happy with the end result however please take a peek out how the source code of ReactiveUI is now structured on the fileystem and how we multi-target multiple platforms using single projects and Life for maintainers that target multiple platforms with dotnet is much better now than ever before. We were able to eliminate so much msbuild technical debt.

Big thank-you to Olly Levett who did the bulk of the conversion. Mate - you are like Mike Rowe - you did the dirty job and if you take a peek at Prism, MvvmCross and other upcoming projects you'll see that they followed your lead. Be proud of what you have accomplished.

Thank-you to Oren Novotony for your guidance, Immo Landwerth for your educational guidance on netstandard and David Kean who helped immensely with troubleshooting Visual Studio 2017 stability problems we encountered way back in the early days during this time of epic change. Rob Relyea please keep the communication channels open with the community because how we release software will be changing within the next month or so to a continuous delivery model. The ReactiveUI community has grown, we have new maintainers and our testing automation has matured to a point where will be releasing faster from this point onwards because we can. Consumers of ReactiveUI will no longer need to use our MyGet feed.

ICYMI - At MVP Summit, the community met with Microsoft and with their support and encouragement we forked control of System.Reactive. Head on over to this blog post for specifics as to what this means for the future of Reactive Programming on .NET.

You may or may not know this but ReactiveUI is maintained by unpaid volunteers. We put up a big marketing front but at its core is a couple of passionate folks. Open-source as it is today is unbalanced and broken. If you’re relying on open-source software for your business and you haven’t secured your supply chain, you’re negligent. For the longest time the software industry has talked about open-source software in the terms of user freedom, but we have never stopped to think about the cost. The cost is too high. Lana Montgomery, thank-you for sponsoring Geoff's attendance to LinuxConfAu where it was confirmed that this is indeed a cross ecosystem and industry wide concern.

It has been amazing and humbling experience seeing other maintainers of dotnet projects also come to the same realisation as us. Due to their observations they are now implementing measures to restore the imbalance of open-source software. For any maintainers still on the fence about this topic please open a conversation with us on our slack channel and we'll share with you ideas and guide you through your setup. ReactiveUI is now a vibrant community of developers from 22 timezones that supports the projects they depend on. Reactive programming in .NET is now financially subsidised to the tune of $7,580USD per year by community crowdsourcing and corporate sponsorship. We are on track to exceed $10,000USD by the end of 2018.

Thank-you to our backers who are making sustainable open-source a reality:

Thank-you to every single person who shipped a pull-request into this release.

  • Alexey Zimarev
  • Benjamin Tam
  • Damien Doumer Tohin
  • David Nelson
  • Dominik Mydlil
  • Geoffrey Huntley
  • Giusepe Casagrande
  • Glenn Watson
  • Grzegorz Kotfis
  • Jeremy Koritzinsky
  • Jon Stødle
  • Kent Boogaart
  • Martin Björkström
  • Olly Levett
  • Oren Novotny
  • Robert
  • Rodney Littles II
  • Shane Neuville
  • Stefan Moonen
  • Taylor Buchanan
  • Tim Jones

If you can't (or won't) help out financially, then please donate your time. Join the conversation over at and ask how you can help. Thanks for any support you can offer if you decide to - Geoffrey Huntley

New Features

We kept getting reports from folks who want to contribute to the project but their employer has a restrictive list of pre-approved licenses and MSPL isn't on that list. So what if we enabled those to help us? It would be much easier than making them go through internal corporate bs. So that's what we have done - ReactiveUI is now available under the MIT licence. This means we are now fully compatible with the GPL and are in alignment with .NET Core, CoreCLR, CoreFX, Roslyn and Xamarin Forms.

This is the first release of ReactiveUI since joining the .NET foundation. It contains security features that allow you to verify the authenticity of assemblies provided by us.

This is a housekeeping release to ensure that ReactiveUI is in a good position going forward. We have removed a massive amount of maintainer technical debt. The public API surface of ReactiveUI has not regressed in any way and we added automatic tests that validate this as part of the release. We will be adding additional features such as automated on-device, end-to-end integration tests in the coming months to make the source more accessible and safer for folks to contribute to the project.

We have added netcoreapp20 as a supported platform. You can use ReactiveUI on the server-side. Maintainers are super excited about the future of WebAssembly and it allows you to unit test ReactiveUI using dotnet core unit test libraries.

We also fixed that niggling problem that prevented folks from writing unit tests for ReactiveUI applications using Visual Studio for Mac.


This is a big release so it's up to you to decide when it is best for you to upgrade. We don't recommend holding off on upgrading because of changes in the .NET toolchain. It is now impossible to compile previous releases below this release. Know that the maintainers and community of ReactiveUI have been running 183 editions of alpha releases in production over the last eight months. Yesterday we went through and manually tested every platform and are only weeks away from adding full end-to-end regression tests. To us, it's risker to hold off upgrading - we recommend that if you haven't started your netstandard upgrade spike that you do it so now. The longer you hold off on the upgrade the more pain you will experience consuming opensource in the post netstandard world.

When you install ReactiveUI we will bring in the correct version of System.Reactive (currently 3.11) as part of installation as a transitive reference. You'll need to manually remove/upgrade all references to the Reactive Extensions that are below 3.11 that aren't netstandard. Do not attempt to do binding redirects from 2.x to 3.x series. It won't work. It's not worth it. You'll end up with nothing but being unhappy and have a wasted afternoon.

ReactiveUI is now netstandard20 compatible. We have dropped support for portable class libraries. You may be able to install netstandard20 into your portable class library but both Microsoft and the maintainers of ReactiveUI strongly recommend against doing this as you'll be fighting an uphill battle. The correct path to take is File -> New -> Netstandard library and drag your code into the new project. Then install the netstandard compatible versions of any dependencies that you have.

The first thing you'll notice after creating your netstandard20 class libraries is that the name of the ReactiveUI packages on NuGet have subtly changed. Instead of using - we now use . in our package names. We did this because it allows the maintainers to reserve the namespace of ReactiveUI on NuGet and provide you guarantees that if it's in the ReactiveUI.* namespace then it is an official package that was produced by us. Look for the Blue Tick (tm). The documentation has been updated with instructions of which packages you should install on each platform.

If you target the WPF platform you now need to install the WPF specific package otherwise schedulers won't be wired up and you'll be greeted with an appropriate exception. The documentation has been updated. We had to make this change prevent Visual Studio for Mac from exploding when it encountered an automatically imported reference to Windows.Presentation which prevented these folks from being able to unit test their applications with Visual Studio for Mac.

The .NET toolchain has evolved quite a bit over the last year which provided an excellent opportunity to remove legacy platforms such as Silverlight and Windows Phone 8.x.

ReactiveUI now uses monoandroid80 as the minsdk but you'll be able to target earlier versions of android by specifying the targetsdk compilation option.

The minimum version of .NET framework is now net461 which means you'll need to adjust your unit test projects and WinForms/WPF applications. We chose net461 as it's in alignment with Microsoft's official support policy and net461 is now the default option provided in Visual Studio 2017 when scaffolding File -> New Project.

The minimum version of UWP is now 10.0.16299 aka Fall Creators Update. The maintainers picked this as it felt like a reasonable baseline to us and it helps reduce the amount of SDK's one needs to have installed to be contribute to ReactiveUI. If you need to target anything earlier than this then you will need to compile from source. It's as simple as Right Click -> Change Target -> Compile.

The minimum version of Xamarin forms is now We picked this because it was the latest version available on NuGet when we were publishing the release. If you need to target an older version then you will need to compile from source.

Detailed release notes

As part of this release we had 138 commits which resulted in 113 issues being closed.

All Platforms

  • #1530 housekeeping: use new nuget package names to enable nuget namespace reservation
  • #1522 feature: nameof() overload for ObservableAsPropertyHelper mixin
  • #1498 ReactiveCommand in current 8.0 alpha concurrency problem
  • #1476 InvokeCommand not executed in v8 where v7.4 would
  • #1472 test: use new threads explicitly in message bus test
  • #1461 feature: add approval tests
  • #1456 fix: added netstandard 1.1 build and added clamped system.reactive references
  • #1444 feature: add code snippets for VS, VS4Mac and Rider
  • #1441 core: make ViewContractAttribute.Contract public
  • #1440 Make ViewContractAttribute.Contract public
  • #1439 chore: remove legacy code
  • #1426 housekeeping: added identity signing to NuGet packages
  • #1425 chore: remove SILVERLIGHT #ifdefs
  • #1423 chore: cull Splat methods that were never removed
  • #1416 chore: use pre-release visual studio 2017 sdk to work around tooling issues
  • #1394 chore: tidy up comments in ReactiveNotifyPropertyChangedMixins
  • #1392 test: add additional unit test to cover Activation returning IDisposable
  • #1391 chore: update comments in ReactiveCommand
  • #1390 chore: update logging mixing XML comments
  • #1389 Tidy up comments in legacy ReactiveCommand
  • #1367 fix: pin child packages of our main project be locked to the version that's being built
  • #1355 chore: split platform registrations into platform specific files
  • #1327 First pass at updating to VS2017 csproj file
  • #1304 [Bug] CS1701 / CS1702 System.Runtime reference mismatch
  • #1190 .NETStandard support?
  • #1139 Reference Rx 3.0.0 NuGet packages
  • #780 Running Unit Tests under Xamarin Studio without Xam.Mac

Events Generator

  • #1529 fix: this.Events() was not available for consumption due to assembly name conflicts
  • #1526 reactiveui-events not working for platform projects possibly related to PackageReference style projects
  • #1514 feat: propagate obsolete attributes to generated observables
  • #1495 reactive-ui events doesn't have the WPF target anymore in 8.0 alpha 89
  • #1371 housekeeping: only include events source if present
  • #1359 fix: split xamarin forms events BACK into seperate package to prevent future targeting conflicts

Windows Forms

  • #1462 chore: fix xml doc on ReactiveDerivedBindingListMixins

Universal Windows Platform

  • #1452 fix: set UWP min version to 10.0.10586.0

Windows Presentation Foundation

  • #1556 fix: include xml docs in WPF package
  • #1504 reactiveui-wpf.csproj triggers defect/crash in visual studio for windows when opening reactiveui.sln
  • #1450 fix: min platform should be net452; was net452 before migration to new csproj format
  • #1433 fix: remove duplicate ComponentModelTypeConverter
  • #1427 fix: include theme in Reactive.Wpf
  • #1424 The themes directory hasn't been included in reactiveui-wpf so the templates don't resolve
  • #1406 feature: move wpf out of main package to fix unit testing story on mono and unblock other ui frameworks

Xamarin Android

  • #1589 fix: runtime API check for the Android time picker (#1233)
  • #1519 feature: target monoandroid80 instead of monoandroid70 and upgraded to support lib
  • #1517 VS2017 15.4 issues
  • #1496 feature: added ctors for JNI ownership transfer in ReactiveAppCompatActivity

Xamarin Forms

  • #1493 feature: bumped to xamarin forms 2.4

Xamarin iOS

  • #1485 [iOS] Circular dependency detected 'reactiveui 8.0.0-alpha0089 => System.Reactive 3.1.1 => System.Reactive.PlatformServices 4.0.0-preview00001 => System.Reactive 3.1.1'.
  • #1437 Changed to add pending changes all at the same starting index when using RemoveRange
  • #1405 Raise ViewWillAppear for child even if parent is already visible
  • #1303 Removed all obsolete UNIFIED symbol checks


  • #1606 housekeeping: fix configuration for tizen

  • #1594 chore: use same vs2017 appveyor image for master and develop

  • #1591 docs: add details about developer environment set up

  • #1587 househeeping: resolve broken CI infrastructure

  • #1579 fix: use netstandard 2.0 compatible version of splat

  • #1568 fix ReactiveUI nuget dependency not being pinned correctly

  • #1563 Add .idea to gitignore to simplify use of JetBrains Rider

  • #1554 chore: fix build

  • #1535 build.cake fails if the pwd contains spaces

  • #1532 housekeeping: compile csproj with multiple target frameworks in parallel

  • #1524 housekeeping: remove fully qualified test names in test explorer (#1328)

  • #1518 housekeeping: github has spoken this is the new convention

  • #1515 Add git hash to nuget package / assembly info

  • #1511 housekeeping: net45 legacy project with CPS workaround

  • #1500 housekeeping: the f in wpf is foundation, not framework

  • #1497 housekeeping: fixed broken link to stackoverflow

  • #1490 housekeeping: upload msbuild binlogs even when the build fails

  • #1489 housekeeping: remove && exit 0

  • #1483 housekeeping: specify cake version in bootstrap script

  • #1482 housekeeping: pinned Cake 0.21.0 and tools/addins to current version

  • #1479 housekeeping: move the code of conduct to the website

  • #1478 housekeeping: cleanup of readme, contributing guide, pull-request template, coc, license

  • #1475 housekeeping: copy API approval results to appveyor so maintainers don't need to re-run builds

  • #1474 Cake.PinNuGetDepenencies needs upgrading to Cake 0.22 soon or our builds will break

  • #1471 Build status badge is out of date

  • #1470 Remove

  • #1469 Update to reference 'develop' branch instead of 'master'

  • #1468 housekeeping: don't autoclose dx issues or cx issues

  • #1458 housekeeping: improve stability of CI when re-running a failed build

  • #1454 housekeeping: add license to nuget package

  • #1449 housekeeping: SignPackages throws an exception when it fails

  • #1448 housekeeping: ¯_(ツ)_/¯ and proposal labels won't be autoclosed

  • #1446 housekeeping: upgrade MSBuild.Sdk.Extras

  • #1443 Set TargetPlatformMinVer

  • #1442 housekeeping: update to MSBuild.Sdk.Extras 1.0.9

  • #1436 housekeeping: merged probot message into single line

  • #1435 housekeeping: automatically close stale github issues in a friendly way

  • #1432 housekeeping update ISSUE_TEMPLATE to match website

  • #1431 SignPackages does not throw exception when it fails

  • #1430 housekeeping: ignore cla github labels otherwise release will break

  • #1420 MSB4041: The default XML namespace of the project must be the MSBuild XML namespace

  • #1419 housekeeping: use .NET foundation appveyor infrastructure

  • #1414 housekeeping: nuget packaging :lipstick:

  • #1410 housekeeping: upgraded eventbuilder to vs2017 project format

  • #1408 housekeeping: added .net foundation license headers

  • #1407 housekeeping: bumped next version to be v8

  • #1395 chore: use editorconfig in place of rebracer

  • #1373 chore: remove CommonAssemblyInfo from git

  • #1363 chore: don't publish ReactiveUI-Core as package no longer exists

  • #1358 housekeeping: github labels updated to rename uwp & wpf, drop windows phone/store, add tizen

  • #1357 housekeeping: retrieve System.Windows.Interactivity from NuGet so contributors don't need to install the SDK

  • #1328 Remove fully qualified test names in test explorer

  • #1232 Using RxUI with Rx v3.x possible?

  • #1122 reactiveui-testing v7 does not install into Profile111 (netstandard1.1)


  • #1562 Fix default values for snippet variables in Rider
  • #1506 docs: upgraded version of xam forms and changed ondestroy to use flush instead of shutdown
  • #1502 housekeeping: let's keep cinephile as an xamarin.forms app
  • #1459 documentation: added cinephile application
  • #1457 documentation: added baseline for xamarin.forms sample application
  • #1415 Improve wording on PR template
  • #1412 chore: tweaking comments in TestUtils
  • #1204 docs: email Geoff Huntley, not Anaïs Betts for slack invitation

Where to get it

You can download this release from