

Ashok Selvan replaced Dulquer in the lead role, while actresses Ritu Varma, Aparna Balamurali and Shivathmika Rajashekar were cast in the leading female roles. Several changes were also made to the cast and crew owing to date clashes. In late June 2021, Viacom18 Studios in association with Rise East Entertainment, relaunched Karthik's directorial debut, with the title being changed to Nitham Oru Vaanam, from Vaan. However, the production studio's continued financial problems and the COVID-19 pandemic prompted the film to be continually delayed and later dropped. Priya Bhavani Shankar also joined the film's cast in February 2019. At the event, Kalyani Priyadarshan and Kriti Kharbanda were announced as two of the lead actresses, with Karthik suggesting that the storyline travels from "Chennai to Kolkata" and that the film would be "along the lines of Jab We Met (2007)". The film was launched in December 2018, with a ceremony held in Chennai attended by Dulquer and crew members. Karthik noted that he initially wanted to title the film as Vaanam – after the sky, which changes its form and colour regularly, like the lead character – but the presence of an earlier film prompted him to choose Vaan. Īfter a brief delay, the first look poster of the film was released in June 2018, confirming the identity of the principal crew members. Actress Shalini Pandey joined the cast of the film during October 2017, but production was delayed as a result of Kenanya Films' financial problems. Considering the film's theme of travel, Karthik revealed that the film would be shot across locations including Chennai, Pollachi, Coimbatore, Chandigarh and Nainital. Williams, Sreekar Prasad and debutant Dheena Dayalan joined the team as the film's cinematographer, editor and music composer respectively, while the director stated that the team had planned to begin production by December 2017. In June 2017, Karthik stated that the casting process for the lead actresses was still ongoing, and that there were no plans of making a Malayalam version of the film, despite speculation.

Other actresses including Akshara Haasan, Nazriya Nazim and Parvathy were also considered for the film, though none of them were officially signed on for the project. Described as "romantic entertainer-cum-road movie", Karthik stated that the film would have four lead actresses and that discussions for roles were held with Nivetha Pethuraj and Megha Akash.

Karthik, to be produced by Kenanya Films. The film was first announced to the media in January 2017, when it was reported that Dulquer Salmaan would work on a Tamil film by debutant director R.
