Please see https://releases.xamarin.com/stable-release-cycle-8-service-release-1 for the details about this release, including the steps to update or downgrade as needed.
Please file a quick bug report using the "Cycle 8" new bug form if you see any behavior that looks suspicious in these versions (and if it isn't clear whether one of the known issues in the release notes matches the problem).
Comment in this forum thread if your question is not related to a suspicious behavior after installation, but instead one of the following:
None. This release includes candidate fixes or improvements for each of the higher-visibility known issues that were listed in the forum announcement for the previous release.
You can view the list of bugs addressed by this version using the following Bugzilla query:
Note that the bug numbers in this query include some non-public bugs as well as some bugs that were included in the Stable channel Xcode 8.1 compatibility update from October 27.
You can view all of the remaining bugs that have been reported against the Cycle 8 version that are not yet fixed in "Cycle 8 – Service Release 1" using the following Bugzilla query:
Note that some of the remaining issues on this list are already marked "FIXED." The candidate fixes for those issues are not yet included in this release, but they will be included in a future Service Release or Feature Release.
[Xamarin for Visual Studio], [Xamarin Studio] - Upcoming compatibility feature, tracked in 44330 - "This version does not have support for files saved in Xcode 8 format" appears when attempting to edit a file with the Xamarin iOS designer after having edited the file with Xcode 8. Xcode 8 introduced a new, non-backwards-compatible XML format for Interface Builder documents that is not yet supported in Xamarin's iOS designer. As it turns out, Xcode 8.1 from Apple has in fact backed out of several of those format changes. Candidate fixes are now under test for Xamarin's iOS designer to cover the remaining format changes as present in Xcode 8.1.
[Xamarin Studio] - 43188 - Sporadic "Out of memory" error during build leaves solution in an unbuildable state until the project is reloaded.
EDIT Nov 14: Correct a typo in the fixed bugs query.