League Two side Luton Town sign former Plymouth and Truro City striker Isaac Vassell following a trial spell.
Plymouth Argyle have signed midfielder David Ijaha of non-league Whitehawk following a trial at Home Park.
The managing director of Oxford City Football Club is found dead at the team's ground.
Relegated York will face promoted Maidstone United on the opening day of the 2016-17 National League season.
Grimsby sign York midfielder James Berrett and Sutton United winger Tom Bolarinwa for undisclosed fees.
Colchester United sign former Gillingham versatile left-back Brennan Dickenson and ex-Chelmsford centre-back Dexter Peter.