Apple shares a fix for frustrating ‘Not Delivered’ iMessage bug

Chance Miller | Oct 15 2025 - 2:07 pm PT

Apple today updated a support document with details on why iMessages might show a “Not Delivered” alert, appear as SMS/RCS messages in green bubbles, or come from your email address instead of your phone number.

As spotted by MacRumors, Apple says that these problems might stem from not activating your eSIM when you set up a new iPhone with iOS 26. When you choose to set up your eSIM later in Settings, iMessage does not activate automatically.

This means that after you set up your eSIM in the Settings app, you’ll also need to manually activate iMessage:

In the Settings app, tap Apps.
Tap Messages.
Turn iMessage off and back on.

Top comment by Kyle Jones

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An issue I am having is that in one particular group chat, posts and responses are bifurcating into two seperate threads. I make a post in a thread, someone else responds and it opens into a new thread. Another response - from the same person - will open in the original thread. I can't see all of the posts and responses in the same thread. Strange thing is - if I look at messages on my Macbook - the group chat (and all posts and responses) are normal. It's very frustrating.

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This advice seems to primarily apply to people who skip the eSIM setup step during the initial setup flow of their new iPhone. It might also impact people who switch carriers and set up a new eSIM in the Settings app.

This is at least the second iMessage glitch that has impacted users since iOS 26 was released. Earlier this month, Apple shared another guide on what to do for iPhone users who are unable to activate iMessage with their phone numbers.

Have you had any problems with iMessage since updating to iOS 26 or getting a new iPhone recently? Let us know down in the comments.