If any program or query is failed with error ORA-28759, its should be access/permission issue to the wallets location in database server.
Ex: In my database there is DB link which link to other schema, if i check the db link test i got the below error.
SQL> select count(*) from tab@TEST_DBL;
select count(*) from tab@TEST_DBL
*
ERROR at line 1:
ORA-28759: failure to open file
I find the tnsping is not working and got below error.
TNS-12560: TNS:protocol adapter error
i find there is permission issue to wallet location even directory owner is oracle
oracle@labserver:[DB->TEST]$cd /home/oracle/wallet
-bash: cd: /home/oracle/wallet: Permission denied
i check the permission is not sufficient.
drw-r----- 2 oracle oinstall 113 Nov 5 02:00 wallet
Changed to 755 to oracle and got access to directory and issue resolved.
Like this for any reason if wallet is configured in listener/sqlnet.ora and does not have access wallet directory for oracle user then this issue arise.
Fix by fixing access issue to wallet location.
