The Piano Sonata in A minor D. 784 by Franz Schubert is a sonata for solo piano, posthumously published as Op. 143. Schubert composed the work in 1823, the first sonata written after his illness the year before. A typical performance lasts around 25 minutes. It has been noted that Schubert made a musical allusion in the slow movement of the Arpeggione Sonata to the D. 784 sonata.
