another way of doing backup for all databases, I use this for SQL express backup via sqlcmd/task schedular, BTW you can use SQL agent from standard/developer/enterprise edition to take backup of SQL express instance provided appropriate ports are open and SQL agent have access to express edition/server.
declare @cmd varchar(5000)
select @cmd ='if ''tempdb'' <> cast(''?'' as nvarchar) backup database [?] to disk =''x:\sql_backup\?\?_2017_06_15.bak'''
exec sp_msforeachdb @cmd