Re: Breakpoints aren’t hit when attaching custom pipeline component to Btsntsvc.exe

It is not necessary to GAC Pipeline Components; BizTalk will look in the Pipeline Components folder here — C:\Program Files (x86)\Microsoft BizTalk Server 2013 R2\Pipeline Components.  However, if you do inadvertently GAC your Pipeline Component, i.e. if you import an MSI containing the component (and you have 'GAC on Import' or one of the other GAC-ing options selected) you will run into this problem.  The best thing to do is search the GAC here: C:\Windows\Microsoft.NET\assembly\GAC_MSIL and if you have a folder in this folder named after your Pipeline Component, then delete that folder.  BizTalk will then return to looking for your pipeline component in the C:\Program Files (x86)\Microsoft BizTalk Server 2013 R2\Pipeline Components folder (after failing to find it in the GAC).  You *should* need to stop the BizTalk Host Instance (that's running the Send Port or Receive Location containing a Pipeline that's using your Pipeline Component) in order to copy a new version of the DLL into the C:\Program Files (x86)\Microsoft BizTalk Server 2013 R2\Pipeline Components folder.  Windows *should* tell you that the file (DLL) is in use and cannot be overwritten.  So if you can copy a new version of the DLL into the C:\Program Files (x86)\Microsoft BizTalk Server 2013 R2\Pipeline Components folder then that's a sure sign that your Pipeline Component is GAC-ed and that's why Visual Studio is unable to go into Breakpoint on the updated code.