Franz Schubert wrote his Impromptus in 1827. These are eight pieces for solo piano, which were later published in two sets of four impromptus each, named Op. 90 and Op. posth. 142 (nowadays they are usually referred to by their Deutsch catalogue numbers, D. 899 and D. 935 respectively). These pieces are usually considered among the most popular examples of the impromptu genre, and they are usually found in recordings toghether with Schubert's Six Musical Moments. The Impromptus were allegedly inspired by the homonimous pieces of Jan Václav Voříšek.
No. 3 from the first set of Impromptus, D. 899, was originally written in G flat major and in 2/4, but the publisher printed it, 30 years later, in G major and 4/4. Nowadays, the original version is favored by most pianists.