In the last couple of weeks we received cases where customers enabled ASP.NET task friendly synchronization in the web.config of their SharePoint servers using web.config entries like the following: <appSettings> <add key=”aspnet:UseTaskFriendlySynchronizationContext” value=”true” /> </appSettings>   From https://docs.microsoft.com/en-us/previous-versions/aspnet/hh975440(v=vs.120):  If this key value is set to false [default], asynchronous code paths in ASP.NET 4.5 behave as […]