Fix WASM boot config ContentRoot to use IntermediateOutputPath by lewing · Pull Request #124125 · dotnet/runtime

lewing · 2026-02-07T03:23:05Z

Summary

Fix a .NET 11 regression causing SRI integrity failures during incremental Blazor WASM builds. Changes in Microsoft.NET.Sdk.WebAssembly.Browser.targets:

Boot config ContentRoot: Change the boot config's DefineStaticWebAssetsContentRoot from $(OutDir)wwwroot to $(IntermediateOutputPath)
Preload matching: Replace fragile %(FileName)%(Extension)-based scanning with direct references to the boot config output items
WebCil ContentRoot (build-time): Use per-item ContentRoot="%(RootDir)%(Directory)" on _WebCilAssetsCandidates so each asset's Identity resolves to its actual file path on disk
WebCil ContentRoot (publish-time): Add per-item ContentRoot="%(RootDir)%(Directory)" on both _NewWebCilPublishStaticWebAssetsCandidatesNoMetadata and _PromotedWasmPublishStaticWebAssets — the same fix applied to publish candidates

Regression

This is a regression in .NET 11 (works in 10.0). It was introduced by dotnet/sdk#52283, which fixed an esproj compression bug by flipping the order in AssetToCompress.TryFindInputFilePath to prefer RelatedAsset (Identity) over RelatedAssetOriginalItemSpec. That fix was correct for esproj, but exposed a latent issue in the WASM SDK targets: the boot config and webcil assets' Identity pointed to a wwwroot copy rather than the actual source files.

Before sdk#52283, OriginalItemSpec happened to point to the real file and was checked first, masking the wrong ContentRoot. After the flip, RelatedAsset (Identity) is checked first, and its stale wwwroot path is used — producing incorrect SRI hashes on incremental builds.

Reported in aspnetcore#65271.

Problem

The WASM boot config file (e.g. dotnet.boot.js) is generated at $(IntermediateOutputPath) (the obj/ folder), but its static web asset was defined with ContentRoot="$(OutDir)wwwroot". This caused DefineStaticWebAssets to compute an Identity pointing to the wwwroot copy rather than the actual file in obj/.

The same issue applied to WebCil asset candidates — files from obj/webcil/, the runtime pack, and other directories were all defined with ContentRoot="$(OutputPath)wwwroot", producing synthetic Identities under wwwroot/ that could become stale during incremental builds.

Fix

1. Boot config ContentRoot

Change ContentRoot to $(IntermediateOutputPath) so the asset Identity matches the real file location on disk. The CopyToOutputDirectory="PreserveNewest" attribute still ensures the file is copied to wwwroot for serving.

This follows Javier's suggestion in dotnet/sdk#52847 to "stop defining these assets with an item spec in the wwwroot folder and just define them in their original location on disk".

2. Preload matching simplification

The _AddWasmPreloadBuildProperties and _AddWasmPreloadPublishProperties targets previously scanned all @(StaticWebAsset) items by %(FileName)%(Extension) to find the boot config asset. This relied on the Identity path containing the fingerprint in the filename, which is an implementation detail of how DefineStaticWebAssets computes Identity based on ContentRoot.

The fix replaces the scanning with direct references to @(_WasmBuildBootConfigStaticWebAsset) and @(_WasmPublishBootConfigStaticWebAsset) — the output items already produced by DefineStaticWebAssets. This is both correct and simpler.

3. WebCil per-item ContentRoot (build-time)

Instead of using a single task-level ContentRoot parameter (which forces all candidates through the same ContentRoot path, causing synthesized Identity for files outside that directory), set per-item ContentRoot="%(RootDir)%(Directory)" on each _WebCilAssetsCandidates item. This means:

WebCil-converted files in obj/webcil/ → ContentRoot = their parent dir → FullPath.StartsWith(ContentRoot) = true → Identity = real FullPath ✅
Runtime pack files (e.g. dotnet.native.js, ICU .dat) → ContentRoot = their parent dir in the runtime pack → FullPath.StartsWith(ContentRoot) = true → Identity = real FullPath ✅

No synthesized paths, no CopyCandidate entries — every asset's Identity is its actual file on disk.

4. WebCil per-item ContentRoot (publish-time)

The publish DefineStaticWebAssets call in ProcessPublishFilesForWasm previously had no ContentRoot at all — neither task-level nor per-item. This caused publish candidates (especially promoted build assets with fingerprint placeholders in their RelativePath) to have their fingerprinted filename baked into the item spec as Identity, producing paths like dotnet.native.7z98fd2ohl.wasm that don't exist on disk → MSB3030 "Could not copy file".

The fix adds per-item ContentRoot="%(RootDir)%(Directory)" on both:

_NewWebCilPublishStaticWebAssetsCandidatesNoMetadata (freshly WebCil-converted publish files)
_PromotedWasmPublishStaticWebAssets (build assets promoted to publish)

Why this works: Promoted assets carry AssetKind=Build from the build-time DefineStaticWebAssets. In DefineStaticWebAssets.cs line 252: IsPublish("Build") = false, so contentRoot is NOT nulled for publish. The per-item ContentRoot = each file's parent directory → candidateFullPath.StartsWith(contentRoot) = true → computed=false → Identity = real FullPath on disk.

What's not changed

Publish boot config ContentRoot (ContentRoot="$(PublishDir)wwwroot"): Publish builds are clean and don't have the incremental staleness problem.

Build Progression

#	Approach	Build Result	Why
1-3	Boot config + preload only	✅ Pass	No WebCil changes
4-5	Per-item ContentRoot (build only)	❌ Fail	Build works, but publish has no ContentRoot → MSB3030
6	Task-level IntermediateOutputPath	❌ Fail	Runtime pack files outside IntermediateOutputPath → synthesized Identity → MSB3030
7	Per-item ContentRoot (build + publish)	🔄 Pending	This commit — applies the fix to both build and publish

Fixesdotnet/aspnetcore#65271

Copilot

Pull request overview

Updates the Blazor WASM SDK targets to define the build boot config static web asset from its actual on-disk generation location (obj/) to prevent stale-asset Identity selection during incremental builds (which can lead to incorrect SRI integrity values at runtime).

Changes:

Change DefineStaticWebAssetsContentRoot for the build boot config asset from $(OutDir)wwwroot to $(IntermediateOutputPath).

Copilot

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Canceled AzDO jobs (typically from timeouts) still have pipeline artifacts containing binlogs. The SendToHelix.binlog contains Helix job IDs that can be queried directly to recover actual test results. Discovered while investigating PR #124125 where a 3-hour timeout caused a WasmBuildTests job to be canceled, but all 226 Helix work items had actually passed.

lewing · 2026-02-08T01:29:45Z

Canceled WasmBuildTests actually passed ✅

The browser-wasm windows Release WasmBuildTests job in build 1284169 was canceled after the 3-hour timeout, but all Helix work items completed successfully.

Recovery steps:

Downloaded the Logs_Build_Attempt1_browser_wasm_windows_Release_WasmBuildTests pipeline artifact
Loaded the truncated \SendToHelix.binlog\ and extracted 12 Helix job IDs
Queried each job via Helix API — all 226 work items passed (0 failures)

Scenario	Server2022	Server2025
NoWorkload-ST	✅ 2/2	✅ 2/2
NoWebcil-ST	✅ 53/53 + 2/2	✅ 53/53 + 2/2
Workloads-ST	✅ 53/53	✅ 53/53
NoFingerprint-ST	✅ 2/2 + 2/2	✅ 2/2 + 2/2

The failure was purely the AzDO job wrapper timing out while waiting to collect results, not an actual test failure.

Canceled AzDO jobs (typically from timeouts) still have pipeline artifacts containing binlogs. The \SendToHelix.binlog\ contains Helix job IDs that can be queried directly to recover actual test results. ## What changed - Added **Recovering Results from Canceled Jobs** section to helix skill SKILL.md - Documents the workflow: download artifacts → load binlog → extract Helix job IDs → query Helix API - Includes concrete example from PR #124125 (226 work items all passed despite 3h timeout cancellation) - Added tip about binlog MCP server for structured binlog analysis ## Context Discovered while investigating #124125 where \�rowser-wasm windows Release WasmBuildTests\ was canceled after 3 hours. The script reported no failures (correct — no *failed* jobs) but also couldn't surface that the tests actually passed. With the documented recovery workflow, the Helix results were fully recoverable.

Copilot

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

…ation - ComputeWasmPublishAssets: Match RelatedAsset by full filename with extension instead of base name only, with webcil .wasm->.dll normalization to avoid ambiguity between .dll/.pdb files sharing the same base name. - LinkContentToWwwroot: Normalize relative ItemSpec paths to absolute using MSBuildProjectDirectory when computing ContentRoot, preventing incorrect paths when working directory differs. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

lewing · 2026-02-26T23:17:39Z

Addressed CCA review feedback in latest commit:

Full filename matching (ComputeWasmPublishAssets.cs): UpdateRelatedAssetProperty now matches by full filename with extension (with webcil .wasm to .dll normalization) instead of base name only, preventing ambiguity between .dll/.pdb files.
Absolute path normalization (LinkContentToWwwroot.cs): Added Path.IsPathRooted check with Path.GetFullPath(identity, MSBuildProjectDirectory) fallback for relative paths in ContentRoot computation.
Hard-coded line number: Replaced (line 448) reference with (above).
Fingerprint/Integrity empty strings: Investigated RemoveMetadata approach but it requires Include, and using Include on the same item group duplicates all items. Empty string via Update is intentional - DefineStaticWebAssets treats it as recompute.

Resolve conflict in Microsoft.NET.Sdk.WebAssembly.Browser.targets: - Adopt upstream Webcil casing (lowercase 'c') for property names - Keep PR's removal of _WasmBuildOuputPath - Fix casing in per-item ContentRoot Update lines to match Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

The upstream Webcil casing change renamed the property to IsWebcilEnabled (lowercase 'c'), but the conflict resolution left references using the old IsWebCilEnabled casing, causing CS0103 build errors. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

…PublishAssets.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

PR dotnet#124905 renamed IsWebCilEnabled to IsWebcilEnabled on main. The merge auto-resolved the parameter name but the error message string interpolation still referenced the old casing. Also improved the error message to include asset details and used 'is null' pattern. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

lewing · 2026-03-02T23:36:48Z

/ba-g failure is an OOM we see without this PR too

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Fix SRI integrity failures in Blazor WASM incremental builds dotnet/sdk#52847
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lewing added arch-wasm WebAssembly architecture area-Meta os-browser Browser variant of arch-wasm and removed needs-area-label An area label is needed to ensure this gets routed to the appropriate area owners labels Feb 7, 2026

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The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#3008
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[android-arm64] The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#6408
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Document canceled job recovery in helix Copilot skill #124135
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Comment thread...nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets

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[wasm/browser] Failed to connect to socket /run/dbus/system_bus_socket #120176
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[wasm] Microsoft.Playwright.TargetClosedException : Target page, context or browser has been closed #121195
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Comment threadsrc/tasks/WasmBuildTasks/LinkContentToWwwroot.cs
Comment threadsrc/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ComputeWasmPublishAssets.cs

lewing force-pushed the fix/wasm-compression-stale-files branch from 420afbe to 80ab512Compare February 26, 2026 23:15

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[wasm] OpenQA.Selenium.WebDriverTimeoutException: timeout: Timed out receiving message from renderer #117486
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Comment threadsrc/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ComputeWasmPublishAssets.cs Outdated

lewingand others added 2 commits February 27, 2026 21:47

Merge branch 'main' into fix/wasm-compression-stale-files
c181cdc

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[mono] The type initializer for System.Drawing.DrawingCom threw an exception: Operation is not supported on this platform #110150
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CharClassSubtraction_DeepNesting_DoesNotStackOverflow fails with PlatformNotSupportedException on browser-wasm (NonBacktracking) #125020
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Merge branch 'main' into fix/wasm-compression-stale-files
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Update src/tasks/Microsoft.NET.Sdk.WebAssembly.Pack.Tasks/ComputeWasm…
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…PublishAssets.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

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[android][arm64] System.Net.Sockets.Tests.SendTo_SyncForceNonBlocking.Datagram_UDP_ShouldImplicitlyBindLocalEndpoint fails with NetworkUnreachable #120526
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[main] Source code updates from dotnet/runtime dotnet/dotnet#5186
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Fix WASM boot config ContentRoot to use IntermediateOutputPath - #124125

Fix WASM boot config ContentRoot to use IntermediateOutputPath#124125
lewing merged 18 commits into
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lewing commented Feb 7, 2026• edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Regression

Problem

Fix

1. Boot config ContentRoot

2. Preload matching simplification

3. WebCil per-item ContentRoot (build-time)

4. WebCil per-item ContentRoot (publish-time)

What's not changed

Build Progression

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lewing commented Feb 8, 2026• edited Loading Uh oh! There was an error while loading. Please reload this page.

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Canceled WasmBuildTests actually passed ✅

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lewing commented Feb 26, 2026

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