A tumultous couple of years has ended in heartbreak for Barca, who had done everything possible to keep their talisman at the Nou Camp, only to be undone by financial constraints as they battled to offload players and jump through hoops to cling on to the superstar.
The club blamed LaLiga over 'economic obstacles' that prevented them from handing him a lucrative new deal, with the player reportedly U-turning on his decision to re-sign amid anger over his pay-cut, as well as at the state of the squad.
But where did it all go for wrong for Messi at a club that worshipped him, and where he once vowed to stay for life? Barca have struggled in recent years after losing their grip on LaLiga and the Champions League - while internal drama has been rife amid anger at previous chief Josep Bartomeu and new election process.Insurance Loans Mortgage Attorney Credit Lawyer
Here, Sportsmail wades through a dramatic couple of years for Lionel Messi that ultimately sealed his exit from Barcelona.
Lionel Messi will not continue on with Barcelona next season after a dramatic U-turn on his decision to re-sign with the Catalan outfit
It pulls the curtain on 21 years with the club, a story that has ended in bitter fashion
ROW OVER VALVERDE SACKING
Luis Enrique left Barcelona in May 2017 as their most successful manager since Pep Guardiola - winning two LaLiga titles and the Champions League - so it was always going to be a tough act to follow for Ernesto Valverde.
Valverde still managed to deliver two league crowns, but he was sacked midway through the 2019-20 campaign with Barca struggling to keep rivals Real Madrid at bay in the title race - but club director Eric Abidal raised eyebrows by dumping the blame on the players.
He claimed they 'weren't working hard' for the boss, which ultimately led to the board's decision to get rid.
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Messi and his Barca team-mates came under fire after Ernesto Valverde was sacked in 2020
'Many players weren't satisfied or working hard and there was also an internal communication problem,' he said. 'The relationship between the coach and the dressing room has always been good but there are things as an ex-player that I could smell. I told the club what I thought and we reached a decision (on Valverde).'
Messi was far from happy and issued a retort on social media - circling an image of Abidal's quote and insisting Barca directors had to be 'responsible for their decisions'.
He was also furious at Abidal loosely discussing the entire squad rather than individuals in blaming them for his sacking.
Club director Eric Abidal (R) said the board were forced to sack him after the players stopped 'working hard' for the coach
Messi issued an angry retort at his old team-mate, telling chiefs to take responsibility
'Sincerely, I don't like to do these things but I think that people have to be responsible for their jobs and own their decisions,' he wrote on Instagram.
'The players (are responsible) for what happens on the pitch and we are the first to admit when we haven't been good. The heads of the sports department have to take their responsibilities too and above all own the decisions they make.
'Finally I think that when you talk about players, you have to give names because if not, it makes everyone dirty and gives air to things that are said which are not true.'
SOCIAL MEDIA SCANDAL
An incredible report in Spain had claimed that Barcelona hired a social media company called I3 Ventures to damage the reputations of key players such as Messi and Gerard Pique while protecting the reputation of former president Bartomeu and the board.
Radio station SER Catalunya alleged that the objective was to 'erode the image of people and entities that have relations with the club to a different degree' - with the firm said to have been behind dozens of 'unofficial' Facebook and Twitter accounts attacking the images of Messi and Pique.
Barcelona said it 'roundly' denied any relationship with I3 Ventures or links to any company that had been broadcasting disparaging messages about its current players or former managers.
Messi was allegedly the target of a social media campaign by his own club Barcelona
Bartomeu chimed in to bat away the claims as 'flatly false', with the club threatening legal action against any media organisation that 'implicated the club in this practice'.
'Barca has never hired a service to discredit anyone,' he said. 'Not a player, not a former player, nor any politician, manager, president or former president.'
Bartomeu added: 'That is flatly false. We will defend ourselves where necessary on this issue, by all means.'
Barcelona had already threatened legal action against any media organisations that 'continue to implicate the club in this type of practice'.
'Let one thing be clear,' he continued. 'To the question: Have we commissioned the monitoring of social networks? The answer is yes.
Former president Josep Bartomeu was forced to deny allegations that the club had employed a social media company to attack Messi and defender Gerard Pique
'To the question: Have we commissioned to discredit people or institutions through social networks? The answer is no and we will take action against all those who accuse us of that.'
Messi broke his silence on the matter to call the developments 'strange'.
'The truth is that I find it strange that something like this happens,' Messi said in an interview to be published on Thursday by Catalan newspaper Mundo Deportivo.
'But they also said that there would be evidence. We will have to wait to see if it is true or not. We cannot say much and wait to see what happens with all this. It seems a strange issue,' added the Barca captain.
'The president told us the same thing he said publicly, the same thing he said at the press conference. What was the situation, what had happened. I can't say much more,' Messi said.
TENSION WITH BARTOMEU AND SETIEN
It is no secret that Messi did not see eye-to-eye with Bartomeu, and the mystery over the social media claims hardly did anything to repair that relationship.
After finally agreeing to stay at Barcelona last summer, he opened the curtain on his relationship with the former president, claiming he had 'cheated' him in 'many ways'.
'In many things,' he said. 'True, in many ways. I don't want to bring everything out in public, because I don't like to talk about private moments that happened at the club.
'I won't say what was said and promised, but I can assure you that Bartomeu cheated a lot and for several years.'
Messi and Bartomeu did not see eye to eye and he accused him of 'cheating' him 'in many ways'
The forward also had a fraught relationship with Quique Setien, who didn't last long in charge
When Messi first made his desire to leave known, angry Barca fans flocked to the gates of the Nou Camp and demanded that Bartomeu resign.
His eventual resignation opened the door for Messi to pen