ShotgunPublishError : HTTP Error 503

This error is happening some times when Artists try to publish, the error is not present every time but it happens some times, it does for many Artists working and publishing from remote locations using the same remote pipeline configuration.

File “C:\Development\Mighty\repo\mty-config-default\hooks\tk-multi-publish2\maya\”, line 1050, in register_abc_publishes
sg_publish = sgtk.util.register_publish(**args)
File “C:\Users\render\AppData\Roaming\Shotgun\mightyanimation\p157c463.basic.desktop\cfg\install\core\python\tank\”, line 514, in wrapper
response = func(*args, **kwargs)
File “C:\Users\render\AppData\Roaming\Shotgun\mightyanimation\p157c463.basic.desktop\cfg\install\core\python\tank\util\shotgun\”, line 353, in register_publish
raise ShotgunPublishError(error_message="%s" % e, entity=entity)
ShotgunPublishError: Unable to complete publishing because of the following error: HTTP Error 503: Service Unavailable.