Franz Schubert was one of the great tune-smiths of classical music, whose melodies have a distinctive freshness and yearning poignancy - perhaps due to his youthfulness (he died aged just 31, and before he could become famous).
In the early 20th century, somebody had the good idea of making an operetta from some of Schubert's most appealing tunes - and this appeared in various version and under various names including (in English) Lilac Time.
Unfortunately, the plotting and words of these linked Schubert operettas can most kindly be described as 'corny' - and none have been good enough to survive as a standard part of the professional operatic and recording reparatory, although neither have they disappeared - especially from amateur societies.
I have myself sung excerpts from Lilac Time in a concert performance; and watched a performance of the whole thing - which was dramatically dull, and amateur-ish; providing enjoyment mainly from its frequent and extreme elements of coarse acting.
Nonetheless - considered as a piece of music, Lilac Time seems to be among the most enjoyable compilations-adaptations of Schubert's genius for melody - and can be appreciated as such.