Bristol Rovers' 94-year stay in the Football League has ended after they lost at home to Mansfield Town.
Colin Daniel's first-half strike was enough to condemn the Gas to their fate, despite having plenty of opportunities.
Their relegation was further soured by crowd trouble after the final whistle with police having to control the home support.
Northampton Town were nearly in trouble themselves when Ryan Williams put Oxford United ahead at Sixfields.
However, two quick-fire goals from John Marquis and Ivan Toney turned the game around for the Cobblers, who eventually ran out 3-1 winners.
At the top of the table, Rochdale led at Newport County and were in pole position to lift the championship trophy, before goals from Aaron O'Connor and Kevin Feely condemned them to defeat.
The other team in the title picture, Scunthorpe United, raced into a two-goal lead at home to York City and also found themselves in prime place to take the trophy as Chesterfield trailed.
However, two second half goals saw Scunny end up with a point, but still earn promotion.
Elsewhere, Portsmouth's promising finish to the season under Andy Awford ended with a 3-3 draw at home to Plymouth Argyle.
Two goals from James Gray were enough to give Accrington Stanley a winning finish to the season against AFC Wimbledon.
Exeter finished a tough season on a high when they beat Hartlepool United 2-0 at Victoria Park.
There were also wins for Dagenham & Redbridge away to Cheltenham Town and for Southend United at home to fellow playoff challengers Burton Albion.
Morecambe ended their season with a goalless draw against Bury.
Results in full: Accrington Stanley 3-2 Wimbledon, Bristol Rovers 0-1 Mansfield Town, Cheltenham Town 2-3 Dagenham & Redbridge, Chesterfield 2-1 Fleetwood Town, Hartlepool United 0-2 Exeter City, Morecambe 0-0 Bury, Newport County 2-1 Rochdale, Northampton Town 3-1 Oxford United, Portsmouth 3-3 Plymouth Argyle, Scunthorpe United 2-2 York City, Southend United 1-0 Burton Albion, Torquay United 0-3 Wycombe Wanderers