I thought i would reshare how to find the PID of an AppPool, as it's not the easiest thing to find if your not familiar with the process.
This allows you to map the w3wp process to the AppPool that you are trying to diagnose.
Step1 - Open IIS Manager, go to the root node in the tree on the left that represents your computer (should be labelled as your computer name)
Step2 - In the features view to the right, you'll see a section called IIS. Under that you'll see Work Processes.
Step3 - Select that and it should show you all running worker processes and some basic info, including Process ID (PID)
Step4 - You can map that Process ID to the matching process in the Process tab in Task Manager.
This is a repost, the original post can be found on the MSDN Blogs here.
I came across an issue after updating my Visual Studio version to 15.5.3 which would cause my solution to throw an exception whenever it tried to access the database.
System.IO.FileLoadException: 'Could not load file or assembly 'System.Data.SqlClient, Version=126.96.36.199, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)'
The fix for this is nice and easy, you just need to install the NuGet (V4.4.2) package System.Data.SqlClient.