Problem:

While start up crs, got below error.

$ crsctl start crs
CRS-4013: This command is not supported in a single-node configuration.
CRS-4000: Command Start failed, or completed with errors.

Solution:

In the standalone grid, there will not  any crs. Only has component will be there.

$ ./crsctl start has
CRS-4123: Oracle High Availability Services has been started.