Enable IDNA 2008 in Non-Transitional Mode for URL processing, aligning Chrome's behavior with Firefox and Safari. Chrome currently uses IDNA 2008 in Transitional Mode in URL processing. The main difference between Transitional and Non-Transitional Mode is the handling of four characters known as deviation characters: ß (LATIN SMALL LETTER SHARP S), ς (GREEK SMALL LETTER FINAL SIGMA), ZWJ (Zero width joiner) and ZWNJ (Zero width non-joiner). In Transitional mode, deviation characters are handled the same as IDNA2003: ß is mapped to ss, ς is mapped to σ, and ZWJ and ZWNJ are deleted. In Non-Transitional mode, domains containing these characters are allowed in domain names without mapping, and thus can resolve to different IP addresses. For example, typing "faß.de" in Chrome and Firefox opens different sites today. Enabling Non-Transitional IDNA in Chrome will allow deviation characters in domain names. Firefox and Safari already made this change in 2016 and continue to use Non-Transitional URL processing.
Non-Transitional IDNA will allow deviation characters in domain names in Chrome, aligning Chrome's behavior with Firefox and Safari.