COM Exception in CRM.

Hello all..

i can't found root cause so asked this.. thank you in advance.

we use CRM 2013 On Prem version and it install to 2 server and connected L4.

today.. i found failure and 1 server a lot of make errors.

System.Runtime.InteropServices.COMException: Microsoft Dynamics CRM has experienced an error.

Reference number for administrators or support : 

i quickly restart IIS and CRM Async services and as soon errors disappear

but i can't found error root cause and logs...

please give a advice.. (check point or prevent step.. )

thank you.