The Blaugrana great's contract at Camp Nou expired at the end of last season, but he was expected to commit to a new deal ahead of the coming campaign.
Messi reportedly agreed a 50 per cent reduction in wages, with news of the contract anticipated this week ahead of Monday's Joan Gamper Trophy match against Juventus.
But Barca's dire financial situation means they are unable to register new players due to La Liga's salary restrictions.
Messi, like new signings Sergio Aguero, Memphis Depay, Eric Garcia and Emerson Royal, had been left in limbo.