• The latest features and API requires Xcode 9.1 and the bundled macOS SDK;
  • Apple Xcode 9.1 requires a Mac running OSX 10.12 (Sierra) or newer;

What's New

This release is built upon our open sourced SDK, using the d15-5 branch and is based on Mono 5.4 (2017-06).

This release introduces macOS APIs added in Xcode9 and Xcode 9.1.

Miscellaneous Enhancements


  • 57535 - [generator] Add enum support for [FieldAttribute]
  • 57537 - [generator] [BindAs] support on Fields

Bug Fixes

  • 58411 - [bcl] TrustFailure (CertificateUnknown) when using user-installed root certificates
  • 58720 - [security] SecKeychain.QueryAsData returns invalid data type
  • 59247 - [webkit] WKNSURLAuthenticationChallenge could not be registered
  • 59617 - [registrar] Fix static registrar to detect invalid type usage
  • 44027 - [bcl] Chunked HTTP PUT times out
  • 58826 - MMP does not handle platform assembly swapping when a dependency using XM comes first in 32-bit
  • 58849 - [mmp][mtouch] Print verbosity using an invariant culture
  • 58861 - dynamic-symbol-mode does not work with 32-bit mac libraries
  • 59364 - [runtime] Assertion at dynamic-image.c:209, condition prev == MONO_HANDLE_RAW (obj) not met
  • 60317 - [bcl] WebRequest hangs on TLS/SSL usage (
  • 60625 - [runtime] Assertion at local-propagation.c:562, condition ins->opcode > MONO_CEE_LAST not met (
  • 61002 - [bcl] Runtime exception: Cannot access a disposed object. Object name: 'MobileAuthenticatedStream' (

API diff

The following documents contains a complete list of the API changes since our previous stable release:

Xamarin Workbook

If it's not already installed, install the Xamarin Workbooks app first. The workbook file should download automatically, but if it doesn't, just click to start the workbook download manually.