While installing OEM12c, I ran into below error:
ORA-12547 TNS lost contact
There can be different reasons of this issue, but usually the problem is in wrong privileges/ownership of some Oracle binaries located in $ORACLE_HOME/bin directory. Perhaps, Oracle database binaries were installed / linked not correctly or something or somebody has changed the files’ ownership. In my case, I by mistake changed the ownership of database files.
Changing the ownership to original user resolved the issue.