Hi Andreas. We have the same issue. The issue is connected to the CPU spikes that correlate with long GC times.
2018-02-13 16:25:26 [000026f4] severe [dotnet] Exception during ExecuteProcessRequestEntry
2018-02-13 16:25:26 [000026f4] info [dotnet] Server cannot append header after HTTP headers have been sent.
at System.Web.HttpResponse.AppendHeader(String name, String value)
at DynaTrace.Diagnostics.Agent.Introspection.AspDotNetIntrospection.HttpRequestInfo.g(String V, String i)
at DynaTrace.Diagnostics.Agent.Introspection.AspDotNetIntrospection.g(Object V, Object i, Int32 y, Int64 A, Int64& E, Int16 H, Int32 W, Object t, Boolean P)
was there a resolution provided for the error you encountered or is there further information that can be provided as to the cause of this issue as we are facing the same error from one of our .NET instrumented applications