SQL server agent failing some times. "Unable to connect to SQL Server '(local)'. The step failed."

i have a sql server job scheduled to run daily twice.

the job is running fine , but once  or twice a week the job fails saying.

all other times the job runs successfully. it randomly the job is failing. once its failed and if i try to run it manually it runs fine or it will start running fine from next schedule onwards.

This job mainly executes a stored procedure.

the owner of the job is setup as sa. i don't understand why its fail randomly and all other times(90% of cases) it successful.

any help is appreciated.