About the Spring Waltz
According to YouTube the second most popular piece composed by famous polish composer Frédéric Chopin (1810-1849) is his so-called Spring Waltz.

But... did Chopin really write a Spring Waltz? Well... no, Frédéric Chopin composed numerous waltzes but the Spring Waltz was not one of them. The actual piece playing in all of these videos is Mariage d'Amour composed by french composer Paul de Senneville in 1979. Furthermore it doesn't alleviate the confusion that this piece exists in two versions: the original version which is performed by Richard Clayderman and a rearranged version performed by George Davidson. The "Spring Waltz" is the George Davidson version. Listen to the piece below.
It's not even a waltz!
The first thing you may notice when you hear the piece is that it's not even a waltz. It's written in 4/4 and a waltz is written in 3/4. If you are a regular listener of classical music this will probably also stand out for you as something written in present time. Classical music is often far more complex. So why this confusion? Well, I personally believe it was a popular YouTube upload titled "Chopin - Spring Waltz" which caused the whole thing (but I can't know for sure). The video has now been removed (and replaced by others) but I think it reached around 25M views - that exact video even fooled me! :(
Does a Spring Waltz exist?
How the uploader even came up with the title is mysterious since I can't find a single piece called Spring Waltz - the title doesn't even seem to exist anywhere except for a Japanese TV show which, I guess, doesn't have too much to do with Chopin. If you've heard about an actual piece called Spring Waltz let me know in the comment section.
I hope I was able to clear up the confusion about this piece. Unfortunately, I think the power of social media will make it hard to erase this mistake whatsoever. Remember, this is a beautiful piece which deserves to be credited appropriately.