BUG #15905: FATAL: the database system is starting up

The following bug has been logged on the website:

Bug reference:      15905
Logged by:          Aayush chaturvedi
Email address:      chaturvedi98293@gmail.com
PostgreSQL version: 11.4
Operating system:   Windows 64 Bit
Description:

Hi Team,

I was working on server and suddenly my PC got off. When i restarted my PC i
am getting the error message "FATAL: the database system is starting up". I
am new to Postgre and this was the Master server having no backup at all.
With this server some of the users were connected as well.
Could anyone please help asap.

Some of the logs :
2019-07-12 12:25:53.720 IST [7856] LOG:  could not open file
"pg_tblspc/16817/DB2/BIN/db2compr.dll": sharing violation
2019-07-12 12:25:53.720 IST [7856] DETAIL:  Continuing to retry for 30
seconds.
2019-07-12 12:25:53.720 IST [7856] HINT:  You might have antivirus, backup,
or similar software interfering with the database system.
2019-07-12 12:26:28.460 IST [7856] LOG:  could not open file
"pg_tblspc/16817/DB2/BIN/db2dasapi64.dll": sharing violation
2019-07-12 12:26:28.460 IST [7856] DETAIL:  Continuing to retry for 30
seconds.
2019-07-12 12:26:28.460 IST [7856] HINT:  You might have antivirus, backup,
or similar software interfering with the database system.
2019-07-12 12:27:07.972 IST [7856] LOG:  could not open file
"pg_tblspc/16817/DB2/BIN/db2dascmn64.dll": sharing violation
2019-07-12 12:27:07.972 IST [7856] DETAIL:  Continuing to retry for 30
seconds.
2019-07-12 12:27:07.972 IST [7856] HINT:  You might have antivirus, backup,
or similar software interfering with the database system.

Thanks,
Aayush