The Imps were expected to challenge for promotion in League Two but were only able to manage a disappointing 13th-placed finish.
Jackson was also left to rue some of his transfer dealings, with some of the players he brought to Sincil Bank unable to fire the club to promotion.
"I know the fans were hanging on my promise of a special season and I know some were annoyed because they feel they have been let down," he told the Lincolnshire Echo.
"I said it because I firmly believed at the time that we were in line for a special season and so too did the players.
"David Graham and Kevin Gall are in that category. Kevin's move didn't work and that happens."