Error connecting ASM ORA-15055: unable to connect to ASM instance Fatal NI connect error 12547 ORA-12547: TNS:lost contact

This Blog is intended to resolve below errors observed in DB alert log file due connectivity issue between DB Instance & ASM disk/Instance


Fatal NI connect error 12547, connecting to:
TNS-12547: TNS:lost contact
    ns secondary err code: 12560
    nt main err code: 517

ORA-15055: unable to connect to ASM instance
ORA-12547: TNS:lost contact
TNS-12545: Connect failed because target host or object does not exist

ERROR: Failed to connect with connect string: (DESCRIPTION=(ADDRESS=(PROTOCOL=beq)(PROGRAM=stance
ORA-12547: TNS:lost contact
,ORACLE_SID=055: unable to connect to ASM instance


$GRID_HOME/bin/oracle or $ORACLE_HOME/bin/oracle permission has got changed

ls -al $GRID_HOME/bin/oracle
-rwxr-x--x 1 grid oinstall 200678464 Feb 28 14:54 oracle

ls -al $ORACLE_HOME/bin/oracle
-rwxr-x--x 1 oracle asmadmin 228886191 Feb 28 15:41 oracle


Change permissions as below

cd $GRID_HOME/bin
chmod 6751 oracle

chmod 6751 oracle

it should look like having sticky bit ..

ls -l $GRID_HOME/bin/oracle
-rwsr-s--x 1 grid oinstall 203974257 May 11 09:30 oracle

ls -l $ORACLE_HOME/bin/oracle
-rwsr-s--x 1 oracle oinstall 232399431 May 14 13:47 oracle

Restart the DB instance post changes .. DB will come up


  1. hi,

    now problem resolved..

    thanks ajay..

  2. thanks! it helped me!

  3. here it is the year 2022 and this post just saved me!