Feed service provider defined identifier is missing

Question

i am trying to access my OneDrive from PWA but as i click on that i get redirect to Newsfeed.

I am also trying to sync my outlook nwith PWA but ending with 2 errors 

1=We couldn't start syncing your tasks because we need to get a few things set up first. Click here to get started, and then retry syncing your tasks.

2= We weren't able to start syncing your tasks because one or more pre-requisites for connecting to Exchange server could not be found. Please contact your administrator to resolve this issue.

Please help me regarding this as soon as possible