Some visas require you to complete formalities after arriving in France. These formalities depend on what is marked on your visa, under the "Remarks" section.

Visa marked "Carte de séjour à solliciter…" or "C.Sej A Sollic."

You must apply for a residence permit corresponding to your visa within two months of arriving in France.

Visa marked "Mineur scolarisé" (school-going minor)

You do not have to complete any formalities on arrival. As soon as you reach the age of majority, you will have to apply for a student residence permit.

Visa marked "Étudiant", "Passeport Talent", or with any other requirement

You must validate your visa online within three months of arriving in France, as soon as you have a fixed address.
To finalize the validation process you will have to pay an excise stamp (“timbre fiscal”), either online by credit card or at a tobacconists ("bureau de tabac") by credit card or in cash.

Once the process has been completed and your visa has been registered as a residence permit, a validation confirmation in PDF format (“Confirmation de la validation de l’enregistrement de votre visa long séjour valant titre de séjour”) will be sent to you by email.
We advise you to print this document and carry it with you at all times, especially when crossing a border.
 
More information
> Consult the Frenquently Asked Questions(FAQ) of the "Direction générale des étrangers en France" (Directorate-General for Foreign Nationals in France)
Updated on April 22, 2021