I was deploying software using the software deployment wizard. but getting an Unexpected HTTP response: 503 Service Unavailable" error.
That would usually indicate the BESRootServer service is stopping, starting, or restarting; or the SQL Database service is stopping/starting/restarting or unreachable from the root server. Check the event logs for messages from these services.
Can you just explain it more please.
If the error is consistent / still ocurring you should open a support ticket so the team can help you review your logs.