I have been getting this same message since yesterday afternoon. I have tried refreshing, clearing history and switching browsers, but the problem still persists.
Server error
The server encountered an error and could not complete your request. A message has been sent to our engineering and support teams to notify us of the problem, and we will fix it as soon as possible.
The Cisco Meraki Dashboard is temporarily unavailable, but rest assured your Meraki equipment is still running and network operation has not been interrupted. Learn more about Meraki's out-of-band control.