send notification error

 

Hi,

I got a send notification fail error 503

what is this error code?

Thanks

 

2017.10.12 09:00:00.396 Notifications: failed send request [503] 

this is the exact msg
 
Since 503 doesn't exist in the list of error codes, I'd assume its 503 Service Unavailable — httpstatuses.com
 

Hmmm.... Means my server offline.

Omg....