Why IIS worker process w3wp.exe is experiencing "Access is denied." in DB2 ?

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One example of the  access denied issue from w3wp.exe  could be experienced with following db2diag.log messages,

2016-06-02-02.35.36.707000-300 E391509H442 LEVEL: Error (OS)               
PID : 6404 TID : 6984 PROC : w3wp.exe                                      
INSTANCE: DB2  NODE : 000 DB : MYDB                                    
APPID : <>                             
EDUID : 6984                                                               
FUNCTION: DB2 UDB, oper system services, sqloEstablishNamespace, probe:    
87                                                                         
MESSAGE : ZRC=0x83000005=-2097151995                                       
CALLED : OS, -, CreateDirectory                                            
OSERR : 5 "Access is denied."       

The most  common reason of similar problem is   incorrect setting of the user  accessing the database.

DB2 is trying to  perform a lower level windows operation using underlying filesystem and experiencing an access denied situation.

Sometimes reinstalling db2 and/or  complaining product might  resolve the issue as the install steps might guide to use correct settings.

This can happen if the user  using w3wp.exe  is not part of  groups DB2USERS or DB2ADMNS                                              

                                                                                           
The  db2diag.log does not show  what the user name who is running    w3wp.exe  .  

To determine which user runs w3wp.exe open Task Manager and look at the process details.  

 If  the extended security  DB2_EXTSECURITY   is set  (default setting is YES)                                                   
the   user need  to be included in those groups.          

One  group at a time could be  included and tested to perform minimal required changes.                         
.                                                                         
Changing group ownership will require an application restart. 

                .                                                                         
This may only take care of the  the db2diag.log entries but the application may still face issues.

Appropriate actions should be taken if the issue is still not fixed after adding to  the groups.