His most famous, and technically difficult, compositions include the sixth of his Polyphonic Studies "Die letzte Rose", and Grand Caprice on Schubert's "Erlkönig".

In April 1829, Ernst left Vienna for Munich for an employment in the royal orchestra, but Paganini advised him to aim for something higher.

Paganini immediately rose up, threw the manuscript under the bed sheet, and said that he had to protect his composition not only from Ernst's ears, but also his eyes.

Paganini couldn't meet the demands of the audience who thought that Ernst's playing had spoken more to the heart.

Paganini then organized another concert and challenged the audience by playing his Moïses, variations on the G string, moving some to tears.

Perhaps out of respect for Paganini, Ernst later composed his own set of variations on the theme Carnaval de Venise, which he often played at the end of his concert.

He performed the viola solo of Berlioz's Harold en Italie many times, including under the direction of the composer in 1842.

He spent the last seven years of his life in Nice, composing works including Polyphonic Studies, Othello-Fantasie and Concerto pathétique.