mv moving file fires callback header issue

I am using mv module from nodeJs to move a file from the current location to other.

Like this:

Plant.find({
            where: {
                id: plantId
            }
        }).then(function (plant) {
            Foto.find({
                where: { id: fotoId, plantId: null },
            }).then(function (foto) {
                currentPath = __dirname + "/../public/" + foto.image;
                pathToSave = foto.image;
                pathToSave = pathToSave.replace("unknown", plant.specie);
                newPath = __dirname + "/../public/" + newPath;
                mv(currentPath, newPath, function (err) {
                    return res.status(400).json({ error: "failed to move file" });
                });
                Foto.update({ plantId: plantId, image: pathToSave }, {
                    where: { id: fotoId }
                }).then(function (result) {
                    return res.status(200).json({ message: "plant identified with success" });
                }).catch(function (error) {
                    return res.status(400).json({ error: "failed to identiy plant" })
                })
            }).catch(function (error) {
                 return res.status(400).json({ error: "Foto not found" })
            })
        }).catch(function (err) {
            return res.status(400).json({ error: "The plant requested doesn't exist" });
        })

important part:

   mv(currentPath, newPath, function (err) {
                    return res.status(400).json({ error: "failed to move file" });
                });

the problem is that i get this error: Can't set headers after they are sent., i think the issue is related to the fact that the mv function doesn't have a success calback so what i do inside is syncronous and in breaks with the return statements.

Any tip about this?

Thank you very much

via Filipe Costa