We're sorry, something went wrong during sync. We'll try again later. (Error code: 0xE402FDE9)

• Edited by hillct Wednesday, February 18, 2015 4:52 PM

Any Any changes before this occurred? Like password chagned then you will need to re-enterthe credentials. Follow this to troubleshoot sync issues in OneNote:

https://support.office.com/en-us/article/Troubleshoot-synchronization-errors-in-OneNote-299495ef-66d1-448f-90c1-b785a6968d45?CorrelationId=e5f002bd-3a8e-440c-9e8f-7d7bdc7dc242&ui=en-US&rs=en-US&ad=US

Also some best practices:

http://support.microsoft.com/kb/2819334