breaking-changes

Microsoft Agent Framework for .NET 1.27.0 makes DefaultHttpRequestHandler throw HttpRequestException when its client-provider callback returns a client for a redirect destination. Here is why that hole existed, what breaks, and how to rewrite the callback.

Grpc.AspNetCore and Grpc.Net.Client 2.85.0 now apply MaxReceiveMessageSize to the decompressed size of gzip and deflate messages. A 260 KB request that inflates to 256 MiB is rejected with ResourceExhausted, but legitimate large compressed payloads can start failing too.

Marten 9.55.0 lowers document aliases, DDL template keys and flat-table upsert function names with the invariant culture. Apps running under tr-TR or az-AZ that store documents in tables like mt_doc_ınvoice must rename them first, or their data appears to vanish.

MSTest 4.4.0 added Span<T> and ReadOnlySpan<T> overloads to Assert.Contains and Assert.DoesNotContain, which made ordinary array and string assertions fail with CS0121 on net8.0, net9.0, or any project below C# 14. MSTest 4.4.1, published on 2026-09-16, adds exact array overloads and constrained forwarders. Two explicit-generic call shapes still fail.

After upgrading to C# 14 / .NET 10, calls like array.Contains, x.Reverse(), and MemoryMarshal.Cast suddenly bind to different overloads or stop compiling. Here is what changed and how to pin the old behaviour where it matters.