Hi;

This is a common issue that can be related to writers or either can be related to several problems related to the post

Original source: https://www.veritas.com/support/en_US/article.TECH126737

Here’s what you can do :

1. Check Exchange Writer backup status is not failed state using on CMD

VSSADMIN LIST WRITERS

2.Update Veritas Backup via live update / Update backup agent on the server

3. Check that there are no network problems between the backup server and the exchange server

Ultimately as per restarting the Exchange Writer can be an overwhelming task please do a schedule with the client a suitable time to restart the server and solve the writer issue ;

That should solve your issue for now;