Backup fails with default number of streams with the error: Failed to start NetBackup COSP process.

Explanation:

This error occurs because the nbcosp service, responsible for making calls to the cloud provider's APIs, is down or crashed.

Workaround:

Do any of the following:

On the backup server, run the following command to start the nbcosp service.
<install_directory>/pdde/pdcr/bin/nbcosp start
On the backup server, start all the NetBackup services, run:
<install_directory>/netbackup/bin/bp.start_all