CIL generation: Object reference not set to an instance of an object.

"CIL generation: Object reference not set to an instance of an object." Err:351

Run full CIL generation using the following steps.

1. Stop the AOS
2. Delete the contents of the bin\XppIL [C:\Program Files\Microsoft Dynamics AX\60\Server\MicrosoftDynamicsAX\bin\XppIL] folder on the AOS server (with backup in place) [not the folders, just the files which are outside the folders - 2003 files in total]
3. Restart the AOS
4. Open AX

5. In AOT, Navigate to Build -> Generate Full CIL

After doing these, if you still get any errors, 

1. Navigate to the individual objects in AOT which are throwing the errors

2. Compile them one after the other.

3. Full Compile Again [Build -> Generate Full CIL]

reference :https://community.dynamics.com/ax/b/dynamicsaxinsideout/archive/2015/11/10/error-in-cil-generation-quot-cil-generation-object-reference-not-set-to-an-instance-of-an-object-quot