Changing SQL Server (MSSQLSERVER) Service Account I am sorry if this has already been answered in the past.
We have SQL Server 2016 which is our Dynamics NAV Database. Currently all backups are stored on local drive of the server. I have been given a task to change the destination of backups to a NAS box network drive. On the maintenance plan I changed the destination path to the network drive \10.##.#.##\databasebackup. I received following error:

Msg 3201, Level 16, State 1, Line 1
Cannot open backup device '\10.##.#.##\databasebackup\navdatabase.bak'. Operating system error 5(Access is denied.).
Msg 3013, Level 16, State 1, Line 1
BACKUP DATABASE is terminating abnormally.

After having a look at SQL Server configuration manager, I found that the Log On As account for SQL Server (MSSQLSERVER) is NT Service\MSSQLSERVER but Log On As account for SQL Server Agent (MSSQLSERVER) is domain service account. The service account used for SQL Server Agent (MSSQLSERVER) has read/write access to the network drive \10.##.#.##\databasebackup. In this case I believe I need to change the Log On As account for SQL Server (MSSQLSERVER) to a domain account, am I correct? If I change the NT Service\MSSQLSERVER to a domain account which has read/write access to the network share, does it break anything?
Thank you in advance for your help.
Correct, it is the service account for the database engine that matters here. Agent is irrelevant (it only tell SQL Server to produce the backup). It shouldn't break anything, but every change should be done with care. And make sure you do the change with the right tool (SQL Server Configuration Manager).