Why is my iPhone failing to update to iOS 18.4?

How is your phone "failing to update to iOS 18.4" if there is no iOS 18.4? The most recent release of iOS 18 is iOS 18.3.1.

About iOS 18 Updates - Apple Support

Apple security releases - Apple Support

IOS 18.4 has not been released yet.

iOS 18.4 hasn't been released and we have no date, when it will be released. It is currently in beta testing for developers only.

nemanja180 wrote:

What happened with IOS 18.4?

[Re-Titled by Moderator]

18.3.1 is the latest version

beta version can't be discussed here, defer to your email on where to ask these types of questions.

You are asking about Beta software, which you can't do here. Per the NDA all beta testers sign, beta can't be discussed at all, even here.