As you may have noticed, Microsoft launched .NET 4.5 last week. The new vesion comes with a host of improvements, including a bunch of new C# features. Check out the announcement for all the details.
We have been trialling .NET 4.5 release candidates for a while and started testing the final version as soon as it came out. After ironing out some kinks, we're happy to report that AppHarbor now supports building, testing and running .NET 4.5 applications.
A few AppHarbor users have reported issues caused by the 4.5 upgrade for a small subset of apps. If you encounter problems, please refer to the usual support channels and we'll help you out.