When connecting to Oracle 12.2 databases from different databases with db link, reco process terminates unexpectedly. This problem is caused by bug 27544973. In order to avoid the problem, either patch 27544973 should be applied or the “_db_link_sources_tracking” parameter should be set to FALSE as follows. The database must be restarted when the parameter is changed.
The errors in the database alertSID.log file are as follows.
Session (1052,50052): RECO logon successful: Inbound connection from client
Session (1052,50052): RECO logon successful: DB Logon User: RECO, Remote Machine: XXXXXXXXX, Program: oracle@XXXXXXX (TNS V1-V3), OS User: oracle
Session (1052,50052): RECO logon successful: Client IP Address: XXXXXXXXX
Errors in file /u01/app/oracle/diag/rdbms/orcl/ORCL2/trace/ORCL2_ora_308247.trc (incident=1926647):
ORA-00603: ORACLE server session terminated by fatal error
ORA-03106: fatal two-task communication protocol error
Incident details in: /u01/app/oracle/diag/rdbms/orcl/ORCL2/incident/incdir_1926647/ORCL2_ora_308247_i1926647.trc
opiodr aborting process unknown ospid (308247) as a result of ORA-603
This helped a lot. Thanks for the post