In 1750 he succeeded Johann Sebastian Bach as Thomaskantor at the St. Thomas School, Leipzig; a post he maintained until his death in 1755.
Upon completing his education he returned to Germany where he served the count as his private musician in Dresden from 1731-1750.
[1] Following the death of Johann Sebastian Bach in 1750, Harrer became his successor as Thomaskantor at the St. Thomas School, Leipzig.
He still held the post when he died in Carlsbad in July 1755,[2] but deputies had had to fulfill his duties on occasion, because of his declining health.
He composed much instrumental music, including 27 symphonies, 24 orchestral suites, 51 flute duets and a number of harpsichord sonatas.