Files with EPUB file extension can be converted to other format, for example, PDF, should our device have issues with opening EPUB files. It is worth mentioning that not all e-book files can be converted. Some may be copyright protected or distributed under license that prohibits their editing.
Their exist many online e-book format converting tools, but some may be just scams. Converting larger collections of e-books is best conducted using dedicated software tools. One of the most popular such tool is Calibre, a free software tool that acts both as an e-book reader and converter. It offers and intuitive GUI and is safe to use.