Anyone who knows the solution to this? We are doing a refresh from ESRI ArcGIS SDE to ArcGIS Online and this is the error that was encountered. How to avoid this? Most of the time I encounter this error, only sometimes that the process becomes successful.
ArcGIS Online Feature Service Writer: Encountered an unexpected error. The error code from the server was '504' and the message was: 'Your request has timed out