Had a problem with the installation of MRCA in a RAC cluster.
This can happen when you are installing the MRCA in a RAC environment and the total length of the description string is longer than 239 chars.
Found this in the logfile of the MRCA assistant:
[SQLPlusAction] Connect string: (DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=abcdefghijklmno01)(PORT=1582))(ADDRESS=(PROTOCOL=TCP)(HOST=abcdefghijklmno02)(PORT=1582))(ADDRESS=(PROTOCOL=TCP)(HOST=abcdefghijklmno03)(PORT=1582)))(CONNECT_DATA=(SERVICE_NAME=INFRA)))
SQL> string beginning "(DESCRIPTI..." is too long. maximum size is 239 characters.
Of course the above hostnames are fake (we have different ones, but just as long).
The strange thing is that not all parts fail. So apparently each assistant uses a different method.
Solution was to use just one or two of the hostnames in the MRCA assistant. It is a RAC cluster - so even one host would be sufficient.