ORA-19504 ORA-12547 ORA-15001 ORA-15055
If you’re face below issues while migrate single instance to Grid standalone instance, this below OTN forums discussion topics will helps you
ORA-19504: failed to create file "+ASM_DATA_DG"
ORA-12547: TNS:lost contact
ORA-15001: diskgroup "ASM_DATA_DG" does not exist or is not mounted
ORA-15055: unable to connect to ASM instance
ORA-12547: TNS:lost contact
https://forums.oracle.com/forums/thread.jspa?threadID=2431846&tstart=0
DBA 