The "GenerateBundle" task failed unexpectedly when publishing app to single file

[Jericho]

My Cake script has separate steps for building my C# console app and publishing the app to a single file. These Cake tasks are very simple and they look like this:

The build task:

DotNetBuild($"{sourceFolder}{appName}.sln", new DotNetBuildSettings
{
	Configuration = configuration,
	NoRestore = true,
});

and the publish task (notice that I am publishing to a single file):

DotNetPublish($"{sourceFolder}{appName}.sln", new DotNetPublishSettings
{
	Configuration = configuration,
	NoBuild = true,
	NoRestore = true,
	PublishSingleFile = true,
	SelfContained = true,
});

Invoking my Cake script results in an unhelpful error message from dotnet:

C:\Program Files\dotnet\sdk\8.0.100\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Publish.targets(1038,5): error MSB4018
: The "GenerateBundle" task failed unexpectedly. [D:\_build\Cake.AddinDiscoverer\Source\Cake.AddinDiscoverer\Cake.Addin
Discoverer.csproj]
C:\Program Files\dotnet\sdk\8.0.100\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Publish.targets(1038,5): error MSB4018
: System.IO.FileNotFoundException: Could not find file 'D:\_build\Cake.AddinDiscoverer\Source\Cake.AddinDiscoverer\obj\
Release\net8.0-windows\win-x64\singlefilehost.exe'. [D:\_build\Cake.AddinDiscoverer\Source\Cake.AddinDiscoverer\Cake.Ad
dinDiscoverer.csproj]
C:\Program Files\dotnet\sdk\8.0.100\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Publish.targets(1038,5): error MSB4018
: File name: 'D:\_build\Cake.AddinDiscoverer\Source\Cake.AddinDiscoverer\obj\Release\net8.0-windows\win-x64\singlefileh
ost.exe' [D:\_build\Cake.AddinDiscoverer\Source\Cake.AddinDiscoverer\Cake.AddinDiscoverer.csproj]
C:\Program Files\dotnet\sdk\8.0.100\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Publish.targets(1038,5): error MSB4018
:    at System.IO.FileSystem.CopyFile(String sourceFullPath, String destFullPath, Boolean overwrite) [D:\_build\Cake.Ad
dinDiscoverer\Source\Cake.AddinDiscoverer\Cake.AddinDiscoverer.csproj]
C:\Program Files\dotnet\sdk\8.0.100\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Publish.targets(1038,5): error MSB4018
:    at Microsoft.NET.HostModel.Bundle.Bundler.GenerateBundle(IReadOnlyList`1 fileSpecs) [D:\_build\Cake.AddinDiscovere
r\Source\Cake.AddinDiscoverer\Cake.AddinDiscoverer.csproj]
C:\Program Files\dotnet\sdk\8.0.100\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Publish.targets(1038,5): error MSB4018
:    at Microsoft.NET.Build.Tasks.GenerateBundle.ExecuteCore() [D:\_build\Cake.AddinDiscoverer\Source\Cake.AddinDiscove
rer\Cake.AddinDiscoverer.csproj]
C:\Program Files\dotnet\sdk\8.0.100\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Publish.targets(1038,5): error MSB4018
:    at Microsoft.NET.Build.Tasks.TaskBase.Execute() [D:\_build\Cake.AddinDiscoverer\Source\Cake.AddinDiscoverer\Cake.A
ddinDiscoverer.csproj]
C:\Program Files\dotnet\sdk\8.0.100\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Publish.targets(1038,5): error MSB4018
:    at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute() [D:\_build\Cake.
AddinDiscoverer\Source\Cake.AddinDiscoverer\Cake.AddinDiscoverer.csproj]
C:\Program Files\dotnet\sdk\8.0.100\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Publish.targets(1038,5): error MSB4018
:    at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingCo
ntext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask) [D:\_build\Cake.Add
inDiscoverer\Source\Cake.AddinDiscoverer\Cake.AddinDiscoverer.csproj]

followed by an exception from Cake:

Error: Cake.Core.CakeException: .NET CLI: Process returned an error (exit code 1).
   at Cake.Core.Tooling.Tool`1.ProcessExitCode(Int32 exitCode) in C:\projects\cake\src\Cake.Core\Tooling\Tool.cs:line 118
   at Cake.Core.Tooling.Tool`1.Run(TSettings settings, ProcessArgumentBuilder arguments, ProcessSettings processSettings, Action`1 postAction) in C:\projects\cake\src\Cake.Core\Tooling\Tool.cs:line 103
   at Cake.Common.Tools.DotNet.DotNetTool`1.RunCommand(TSettings settings, ProcessArgumentBuilder arguments) in C:\projects\cake\src\Cake.Common\Tools\DotNet\DotNetTool.cs:line 64
   at Cake.Common.Tools.DotNet.Publish.DotNetPublisher.Publish(String path, DotNetPublishSettings settings) in C:\projects\cake\src\Cake.Common\Tools\DotNet\Publish\DotNetPublisher.cs:line 48
   at Cake.Common.Tools.DotNet.DotNetAliases.DotNetPublish(ICakeContext context, String project, DotNetPublishSettings settings) in C:\projects\cake\src\Cake.Common\Tools\DotNet\DotNetAliases.cs:line 339
   at Submission#0.DotNetPublish(String project, DotNetPublishSettings settings)
   at Submission#0.<<Initialize>>b__0_7()
   at Cake.Core.CakeTaskBuilderExtensions.<>c__DisplayClass36_0.<Does>b__0(ICakeContext _) in C:\projects\cake\src\Cake.Core\CakeTaskBuilder.Execution.cs:line 26
   at Cake.Core.CakeTaskBuilderExtensions.<>c__DisplayClass39_0.<Does>b__0(ICakeContext context) in C:\projects\cake\src\Cake.Core\CakeTaskBuilder.Execution.cs:line 81
   at Cake.Core.CakeTask.Execute(ICakeContext context) in C:\projects\cake\src\Cake.Core\CakeTask.cs:line 119
   at Cake.Core.DefaultExecutionStrategy.ExecuteAsync(CakeTask task, ICakeContext context) in C:\projects\cake\src\Cake.Core\DefaultExecutionStrategy.cs:line 69
   at Cake.Core.CakeEngine.ExecuteTaskAsync(ICakeContext context, IExecutionStrategy strategy, Stopwatch stopWatch, CakeTask task, CakeReport report) in C:\projects\cake\src\Cake.Core\CakeEngine.cs:line 318
   at Cake.Core.CakeEngine.ExecuteTaskAsync(ICakeContext context, IExecutionStrategy strategy, Stopwatch stopWatch, CakeTask task, CakeReport report) in C:\projects\cake\src\Cake.Core\CakeEngine.cs:line 341
   at Cake.Core.CakeEngine.ExecuteTaskAsync(ICakeContext context, IExecutionStrategy strategy, Stopwatch stopWatch, CakeTask task, CakeReport report) in C:\projects\cake\src\Cake.Core\CakeEngine.cs:line 353
   at Cake.Core.CakeEngine.RunTask(ICakeContext context, IExecutionStrategy strategy, CakeTask task, String target, Stopwatch stopWatch, CakeReport report) in C:\projects\cake\src\Cake.Core\CakeEngine.cs:line 254
   at Cake.Core.CakeEngine.RunTarget(ICakeContext context, IExecutionStrategy strategy, CakeTask[] orderedTasks, String target, Boolean exclusive, Stopwatch stopWatch, CakeReport report) in C:\projects\cake\src\Cake.Core\CakeEngine.cs:line 229
   at Cake.Core.CakeEngine.RunTargetAsync(ICakeContext context, IExecutionStrategy strategy, ExecutionSettings settings) in C:\projects\cake\src\Cake.Core\CakeEngine.cs:line 199
   at Cake.Cli.BuildScriptHost`1.internalRunTargetAsync() in C:\projects\cake\src\Cake.Cli\Hosts\BuildScriptHost.cs:line 87
   at Cake.Cli.BuildScriptHost`1.RunTargetAsync(String target) in C:\projects\cake\src\Cake.Cli\Hosts\BuildScriptHost.cs:line 74
   at Cake.Core.Scripting.ScriptHost.RunTarget(String target) in C:\projects\cake\src\Cake.Core\Scripting\ScriptHost.cs:line 110
   at Submission#0.<<Initialize>>d__0.MoveNext()
--- End of stack trace from previous location ---
   at Cake.Infrastructure.Scripting.RoslynScriptSession.RunScriptAssembly(String assemblyPath) in C:\projects\cake\src\Cake\Infrastructure\Scripting\RoslynScriptSession.cs:line 225
   at Cake.Infrastructure.Scripting.RoslynScriptSession.Execute(Script script) in C:\projects\cake\src\Cake\Infrastructure\Scripting\RoslynScriptSession.cs:line 201
   at Cake.Core.Scripting.ScriptRunner.Run(IScriptHost host, FilePath scriptPath) in C:\projects\cake\src\Cake.Core\Scripting\ScriptRunner.cs:line 172
   at Cake.Features.Building.BuildFeature.RunCore(ICakeArguments arguments, BuildFeatureSettings settings) in C:\projects\cake\src\Cake\Features\Building\BuildFeature.cs:line 99
   at Cake.Features.Building.BuildFeature.Run(ICakeArguments arguments, BuildFeatureSettings settings) in C:\projects\cake\src\Cake\Features\Building\BuildFeature.cs:line 49
   at Cake.Commands.DefaultCommand.Execute(CommandContext context, DefaultCommandSettings settings) in C:\projects\cake\src\Cake\Commands\DefaultCommand.cs:line 76

This problem seems to be exactly the same described in this SO question.

I am using .NET SDK 8, my app is targeting .NET8 and I am using Cake 4.0.0. However, the person who reported the problem in the SO question I linked above used a different SDK and different version of Cake which leads me to believe this problem is not specific to a version of .NET or a specific version of Cake.

This seems to be a problem with dotnet more so than Cake, but I am reporting it here and offering a few workarounds in case it can be helpful to others. After a lot of trial and errors, I came to the realization that the issue is the "build" task is not aware that the app will ultimately be published as a single file and therefore doesn't build my app in a way that is expected by the "publish" task.

I came up with two possible workarounds:

1. You can combine the "build" and "publish" tasks into a single task that invokes DotNetPublish like so (notice "NoBuild=false"):

DotNetPublish($"{sourceFolder}{appName}.sln", new DotNetPublishSettings
{
	Configuration = configuration,
	NoBuild = false,
	NoRestore = true,
	PublishSingleFile = true,
	SelfContained = true,
});

2. You can preserve the separate tasks but instead of specifying "PublishSingleFile=true" and "SelfContained=true" in the Cake script, you move these settings to your .csproj by adding the following two lines:

<PublishSingleFile>true</PublishSingleFile>
<SelfContained>true</SelfContained>

In either case, the result is that the build/publish tasks will play nice with each other and your app will be published as a single app.

I hope this is helpful to someone.