Who contributed to .NET on June 27, 2026?

6 developers shipped this update, including jakobbotsch, pavelsavara, Copilot, ajcvickers, kimjaejung96, and PureWeen.

What were the notable .NET updates?

Fix apphost/bundle creation failure on chmod-hostile filesystems (#129342), JIT: Intrinsify Task/ValueTask factory methods, and [mono][amd64] Fix calling-convention mismatch for small straddling vtypes in shared generics.

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The Wire · Showcase

RUNTIME FIXES PODMAN BUILDS, JIT INTRINSIFIES ASYNC FACTORIES

By RepoJournal · Filed 06:04 UTC on June 27, 2026 · About .NET

6 people shipped this

pavelsavara @pavelsavara 2 cited

Copilot @Copilot 2 cited

PureWeen @PureWeen 2 cited

jakobbotsch @jakobbotsch 1 cited

ajcvickers @ajcvickers 1 cited

kimjaejung96 @kimjaejung96 1 cited

dotnet build now works inside rootless podman containers after a fix for chmod failures on bind-mounted filesystems, while the JIT compiler gains direct recognition of Task and ValueTask factory methods for faster async code.

The runtime team shipped a critical fix [1] addressing a long-standing pain point for developers using rootless podman devcontainers. The issue: bind-mounted Windows folders appear root-owned to non-root container users, causing `File.SetUnixFileMode` to fail with permission errors during apphost and single-file publish operations. This blocks the entire `dotnet build` pipeline in environments like VS Code devcontainers. The fix detects chmod-hostile filesystems and skips the mode-setting step when it's not supported.

In a major performance win for async code, the JIT now intrinsifies Task and ValueTask factory methods [2], directly recognizing `Task.FromResult`, `Task.CompletedTask`, `ValueTask.FromResult`, `ValueTask.CompletedTask`, and their instantiation patterns when used in async context. This eliminates method call overhead for the most common async patterns, a substantial improvement for high-throughput code.

The runtime also landed calling-convention fixes [3] for small straddling value types on amd64, resolving corruption in generic shared code paths where struct layouts crossed the 8-byte boundary. On the WASM front [4], the browser runtime upgraded to standardized exception handling using the exnref proposal, moving away from legacy V8-specific encodings.

EF Core shipped fixes for left-join projections of non-entities [6], which now correctly materialize as null on no-match rows instead of throwing. The team also added Half type support for SQLite [7] and refactored element-type handling to be a creation-time concern [8], cleaning up deferred initialization bugs. Coverage reporting is now wired into the EF Core PR workflow [5].

On the MAUI side, the simulator install step that was timing out macOS official builds is now skipped [10], and the release merge workflow got a branch guard [9] to prevent silent failures.

Action items

→ If running VS Code devcontainers on rootless podman, pull the latest runtime immediately dotnet/runtime [immediate]
→ Review your hot-path async code for Task/ValueTask factory calls; JIT intrinsics are now automatic dotnet/runtime [monitor]
→ Validate EF Core left-join projections if you use LEFT JOIN with non-entity DTOs dotnet/efcore [plan]
→ MAUI maintainers: pull the simulator install skip for your official pack pipeline dotnet/maui [plan]

References

[1] Fix apphost/bundle creation failure on chmod-hostile filesystems (#129342) dotnet/runtime
[2] JIT: Intrinsify Task/ValueTask factory methods ↗ dotnet/runtime
[3] [mono][amd64] Fix calling-convention mismatch for small straddling vtypes in shared generics ↗ dotnet/runtime
[4] [browser] WASM exception handling to use the standardized exnref ↗ dotnet/runtime
[5] Generate and upload code coverage reports ↗ dotnet/efcore
[6] Materialize a left-joined non-entity projection as null on no-match (#30915) ↗ dotnet/efcore
[7] Add Half type support for SQLite ↗ dotnet/efcore
[8] Make primitive collection element type a creation-time concern ↗ dotnet/efcore
[9] Add branch guard to merge-net11-to-release workflow ↗ dotnet/maui
[10] Skip simulator install in official pack pipeline ↗ dotnet/maui

Quick answers

What shipped in .NET on June 27, 2026?: dotnet build now works inside rootless podman containers after a fix for chmod failures on bind-mounted filesystems, while the JIT compiler gains direct recognition of Task and ValueTask factory methods for faster async code. In total, 36 commits and 37 pull requests landed.
Who contributed to .NET on June 27, 2026?: 6 developers shipped this update, including jakobbotsch, pavelsavara, Copilot, ajcvickers, kimjaejung96, and PureWeen.
What were the notable .NET updates?: Fix apphost/bundle creation failure on chmod-hostile filesystems (#129342), JIT: Intrinsify Task/ValueTask factory methods, and [mono][amd64] Fix calling-convention mismatch for small straddling vtypes in shared generics.

WASM RUNTIME SHRINKS 3.6% AS DOTNET HARDENS DEBUGGER EXPORTS

The JIT compiler just cut 815 kilobytes from WebAssembly Core Library by folding address constants into load instructions, while the runtime fixed a silent failure in WASI debugging that would strip metadata from stripped binaries.

dotnet 13 shipped 1-min read

@dotnet 3 days ago

RUNTIME FIXES KERBEROS FALLBACK ON UNIX, APPHOST CONVERTS TO C

The managed SPNEGO implementation now falls back to NTLM when Kerberos credentials go missing on Linux, closing a critical auth gap that broke enterprise deployments [ref:1].

dotnet 120 shipped 1-min read

@dotnet 4 days ago

MACIOS DOCS OVERHAUL SPANS 31 TYPES, ASPNETCORE VALIDATION MOVES TO SOURCE GENERATION

Rolf Bjarne shipped 31 types with proper XML documentation across macios while aspnetcore refactors validation classes out of the public API entirely.

dotnet 25 shipped 1-min read

@dotnet 5 days ago

SQLCLIENT KILLS PLATFORM-SPECIFIC BUILDS, ASPNETCORE HARDENS SIGNALR

SqlClient unified its Windows and Unix code paths without restructuring the NuGet package, collapsing build complexity across the entire SNI layer.

dotnet 97 shipped 2-min read

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