503 Error After Upgrading Magento
Are you getting the error after upgrading Magento Like 503 Error then it must be File permission error and you can resolve this by changing file permission to 644 from 666.
If you have upgraded your magneto using connect manager then you will face this type of Issue and it’s not a big issue you can resolve it by changing file permission.
Service Temporarily Unavailable
Service Temporarily Unavailable The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later
If you see above error then Remove maintenance.flag from your Directory and refresh your site and it will resolve your Problem.