dotnet watch: No hot reload changes to apply.

[danroth27]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

When I run a Blazor Web App using dotnet watch in .NET 9 RC1, the first Razor edit fails with the message "No hot reload changes to apply."

Expected Behavior

The Razor code change applies successfully.

Steps To Reproduce

• Install .NET 9 RC1 SDK
• dotnet new blazor
• dotnet watch
• Edit the h1 in Home.razor

Expected result: Change is successfully applied and shows up in the browser
Actual result: "No hot reload changes to apply." and browser doesn't update, even after refreshing the browser
Workaround: Make multiple edits. Subsequent edits apply.

Exceptions (if any)

No response

.NET Version

9.0.100-rc.1.24452.12

Anything else?

No response

@tmat @phil-allen-msft

[tmat]

Could you please run with --verbose and attach the output?

[danroth27]

Could you please run with --verbose and attach the output?

Sure. Here's the output after I apply two edits. The first edit doesn't seem to do anything and has the "No hot reload changes to apply" message. the second edit succeeds:

C:\Users\user\Desktop\BlazorApp>dotnet watch --verbose
dotnet watch ⌚ Working directory: 'C:\Users\user\Desktop\BlazorApp'
dotnet watch ⌚ Watching with Hot Reload.
dotnet watch 🔥 Hot reload enabled. For a list of supported edits, see https://aka.ms/dotnet/hot-reload.
💡 Press "Ctrl + R" to restart.
dotnet watch ⌚ Running MSBuild target 'GenerateWatchList' on 'C:\Users\user\Desktop\BlazorApp\BlazorApp.csproj'
dotnet watch 🚀 Launched 'C:\Program Files\dotnet\dotnet.exe' with arguments 'msbuild /nologo C:\Users\user\Desktop\BlazorApp\BlazorApp.csproj /p:_DotNetWatchListFile=C:\Users\user\AppData\Local\Temp\tmpvnk53l.tmp /nologo /v:n /t:GenerateWatchList /p:DotNetWatchBuild=true /p:DesignTimeBuild=true "/p:CustomAfterMicrosoftCommonTargets=C:\Program Files\dotnet\sdk\9.0.100-rc.1.24452.12\DotnetTools\dotnet-watch\9.0.100-rc.1.24452.12\tools\net9.0\any\DotNetWatch.targets" "/p:CustomAfterMicrosoftCommonCrossTargetingTargets=C:\Program Files\dotnet\sdk\9.0.100-rc.1.24452.12\DotnetTools\dotnet-watch\9.0.100-rc.1.24452.12\tools\net9.0\any\DotNetWatch.targets" /p:_DotNetWatchTraceOutput=true': process id 3856
dotnet watch ⌚ Process id 3856 ran for 702ms.
dotnet watch ⌚ Watching 17 file(s) for changes
dotnet watch ⌚ Target process is 'C:\Users\user\Desktop\BlazorApp\bin\Debug\net9.0\BlazorApp.exe'
dotnet watch ⌚ dotnet-watch is configured to launch a browser on ASP.NET Core application startup.
dotnet watch ⌚ Configuring the app to use browser-refresh middleware.
dotnet watch ⌚ Refresh server running at wss://localhost:49847,ws://localhost:49848.
dotnet watch 🔥 HotReloadProfile: Default.
dotnet watch ⌚ [BlazorApp (net9.0)] Waiting for application to connect to pipe 1227e168-c015-4086-ad13-e7486a212322.
dotnet watch 🚀 [BlazorApp (net9.0)] Launched 'C:\Program Files\dotnet\dotnet.exe' with arguments '[env:DOTNET_MODIFIABLE_ASSEMBLIES=debug] [env:DOTNET_WATCH_HOTRELOAD_NAMEDPIPE_NAME=1227e168-c015-4086-ad13-e7486a212322] "[env:DOTNET_STARTUP_HOOKS=C:\Program Files\dotnet\sdk\9.0.100-rc.1.24452.12\DotnetTools\dotnet-watch\9.0.100-rc.1.24452.12\tools\net9.0\any\hotreload\Microsoft.Extensions.DotNetDeltaApplier.dll;C:\Program Files\dotnet\sdk\9.0.100-rc.1.24452.12\DotnetTools\dotnet-watch\9.0.100-rc.1.24452.12\tools\net9.0\any\middleware\Microsoft.AspNetCore.Watch.BrowserRefresh.dll]" run': process id 6980
Building...
dotnet watch 🕵️ [1227e168-c015-4086-ad13-e7486a212322] Loaded into process: C:\Users\user\Desktop\BlazorA
pp\bin\Debug\net9.0\BlazorApp.dll
dotnet watch 🕵️ [1227e168-c015-4086-ad13-e7486a212322] Connecting to hot-reload server
dotnet watch 🕵️ [1227e168-c015-4086-ad13-e7486a212322] Connected.
dotnet watch 🕵️ [1227e168-c015-4086-ad13-e7486a212322] Writing capabilities: Baseline AddMethodToExistingType AddStatic
FieldToExistingType AddInstanceFieldToExistingType NewTypeDefinition ChangeCustomAttributes UpdateParameters GenericUpdateMethod GenericAddMethodToExistingType GenericAddFieldToExistingType
dotnet watch ⌚ [BlazorApp (net9.0)] Capabilities: 'Baseline AddMethodToExistingType AddStaticFieldToExistingType AddInstanceFieldToExistingType NewTypeDefinition ChangeCustomAttributes UpdateParameters GenericUpdateMethod GenericAddMethodToExistingType GenericAddFieldToExistingType'
dotnet watch ⌚ [BlazorApp (net9.0)] Build completed.
info: Microsoft.Hosting.Lifetime[14]
Now listening on: http://localhost:5146
dotnet watch ⌚ Launching browser: http://localhost:5146/
dotnet watch ⌚ Solution:
dotnet watch ⌚ Project: C:\Users\user\Desktop\BlazorApp\BlazorApp.csproj 121a9d8c-bbad-48cb-8e15-32f51343da86
dotnet watch ⌚ Document: C:\Users\user\Desktop\BlazorApp\Program.cs 7fc6d014-3575-4efb-9580-2ecec05275ec DE-5D-96-B9-65-0D-B2-FB-EA-5B-3D-06-18-10-EE-0D-6B-A3-23-B4-A0-1A-13-3D-EF-94-03-7B-D9-19-CD-09
dotnet watch ⌚ Document: C:\Users\user\Desktop\BlazorApp\obj\Debug\net9.0\BlazorApp.GlobalUsings.g.cs 42fb68be-ec40-4a98-8ec8-10786528b759 1B-C1-69-10-37-C2-95-25-F4-B1-04-FE-05-A7-7B-BE-F0-40-A2-7C-CE-2A-B7-84-ED-28-22-6F-8C-8B-5E-35
dotnet watch ⌚ Document: C:\Users\user\Desktop\BlazorApp\obj\Debug\net9.0.NETCoreApp,Version=v9.0.AssemblyAttributes.cs c59582d9-8d8e-497e-827b-4fb9f7ecd378 9E-76-49-9C-4E-5C-B6-23-AD-48-89-EA-A9-9B-1A-53-D9-C9-70-EF-CF-90-2D-8B-09-6E-78-A1-9E-E4-28-5D
dotnet watch ⌚ Document: C:\Users\user\Desktop\BlazorApp\obj\Debug\net9.0\BlazorApp.AssemblyInfo.cs 88e4383a-b805-4cf6-a992-ed1de4829f8c E9-A1-E4-77-8D-D3-56-EC-01-56-4D-28-A9-DC-12-B2-87-2F-EC-E5-76-E2-92-6E-F9-D9-0E-60-C8-AF-3C-9F
dotnet watch 🔥 Hot reload session started.
dotnet watch ⌚ Waiting for changes
dotnet watch ⌚ File changed: .\Components\Pages\Home.razor
dotnet watch ⌚ No hot reload changes to apply.
dotnet watch ⌚ Updating diagnostics in the browser.
dotnet watch 🔥 Hot reload change handled in 57ms.
dotnet watch ⌚ File changed: .\Components\Pages\Home.razor
dotnet watch 🔥 Hot reload capabilities: Baseline AddMethodToExistingType AddStaticFieldToExistingType AddInstanceFieldToExistingType NewTypeDefinition ChangeCustomAttributes UpdateParameters GenericUpdateMethod GenericAddMethodToExistingType GenericAddFieldToExistingType.
dotnet watch ⌚ Updating diagnostics in the browser.
dotnet watch 🔥 [BlazorApp (net9.0)] Updates applied: 1 out of 1.
dotnet watch 🔥 [BlazorApp (net9.0)] Hot reload succeeded.
dotnet watch ⌚ [BlazorApp (net9.0)] Refreshing browser.
dotnet watch 🔥 Hot reload change handled in 3819ms.

[tmat]

Might be the same issue as https://github.com/dotnet/AspNetCore-ManualTests/issues/3080, which was fixed by dotnet/roslyn#75029

[tmat]

Can you repro in the latest daily build?

[danroth27]

Can you repro in the latest daily build?

Nope, doesn't repro with 9.0.100-rc.2.24468.2 🎉

[tmat]

Ok to close the issue?