Microsoft.CSharp.RuntimeBinder.Semantics.LangCompiler (Faulting application name: w3wp.exe , Faulting module name: KERNEL32.DLL)

I am looking for a solution for 6 hours already. Please read before marking it duplicate. There are tens of other questions like this but none has valid answer that works on all.

My IIS 8 defaultapppool start crashing all of sudden after 5 threshold warnings of:

A process serving application pool 'DefaultAppPool' suffered a fatal communication error with the Windows Process Activation Service. The process id was '3604'. The data field contains the error number.

And then this is the Event Viewer Error after 5 warnings

Faulting application name: w3wp.exe, version: 8.5.9600.16384, time stamp: 0x52157ba0

Faulting module name: KERNEL32.DLL, version: 6.3.9600.17415, time stamp: 0x545049be

Exception code: 0xc00000fd

Fault offset: 0x0001bb0b

Faulting process id: 0xd04

Yesterday: It crashed once and I just did right click on application pool > start.

Today: It crashed again around the same time (not exact). stopped every 5 minutes 6-7 times then start working normal until now.

Recycling is every 29 hours, and I don't think its recycling.

I installed DebugDiag to log crash dump after the last crash. With the instruction in https://stackoverflow.com/a/18335759/9357872 but no crash after that to see the results. But the regular ongoing log is indicating the following CLR Exception error:

DebugDiag Log:

CLR Exception on thread 4976. DetailID = 10
  ASP.global_asax on thread 4976. DetailID = 2

Microsoft.CSharp.RuntimeBinder.Semantics.LangCompiler on thread 4008. DetailID = 7
  Microsoft.CSharp.RuntimeBinder.Semantics.LangCompiler on thread 4008. DetailID = 7
  Microsoft.CSharp.RuntimeBinder.Semantics.LangCompiler on thread 4008. DetailID = 7
  Microsoft.CSharp.RuntimeBinder.Semantics.LangCompiler on thread 4008. DetailID = 7
  Microsoft.CSharp.RuntimeBinder.Semantics.LangCompiler on thread 4008. DetailID = 7
  Microsoft.CSharp.RuntimeBinder.Semantics.LangCompiler on thread 4008. DetailID = 7
  Microsoft.CSharp.RuntimeBinder.Semantics.LangCompiler on thread 4008. DetailID = 7
  Microsoft.CSharp.RuntimeBinder.Semantics.LangCompiler on thread 4008. DetailID = 7

I read that it is caused by using dynamics and memory leak; which I have never used in the whole website project

What is Microsoft.CSharp.RuntimeBinder.Semantics.LangCompiler ? I see there is something wrong in global.asax

Please help. Thanks.