Here is a list of the first claims of potentially habitable exoplanets that later were found to be incorrect. Now we know that Gliese 581 c is too hot, Gliese 581 d and g do not exist, and HD 85012 is too hot. Only Gliese 667C c survives today as the first confirmed potentially habitable exoplanet. Exoplanet detection and characterization is a very hard science. Original press release and paper links included.
This list was created as part of a presentation on the history of the search for habitable worlds.