iOS 15.4 - iMessage won't active. Error message - "An error occurred during activation."

This very thing happened to me after updating to 15.4. Went back and forth between T-Mobile and Apple, each blaming the other, reset network, reset phone TWICE until that whole iCloud outage was resolved and it coincidentally started working again a few days after it broke. Now it's just started happening again to me. My phone has been on 15.4.1 since it rolled out but it only started this nonsense again today. I too have a T-Mobile e-sim only. May go by the store to pick up a physical sim tomorrow if it hasn't sorted itself out. This is definitely a widespread bug that neither party has really acknowledged and sought to resolve.

I’m T-Mobile as well and I skipped a carrier update and can’t get it to reappear. Guess I need to uninstall and reinstall the cell plan but dubious about doing it.

Apple said via a phone call that they are aware and are working on a patch.

For me it’s a daily thing. I wake up, iMessage has started working again, couple hours later my number is not part of my appleid, I add it, and the “24 hrs” starts over again with it working when I wake up the next day.

jamesbfg wrote:

This might be useful to anyone having issues: https://apple.news/AWBrradTqSiWBWMv2uUYFxw

Apple - Support - System Status

Yesterday I inserted physical sim without number to my phone it turned off cellular, then I removed it and iMessage started to work. It’s been more then 28 hours since then, so hopefully it helped. Before that iMessage worked about 2 hours a day. Fingers crossed.

I am having the exact same issue. I've been on the phone with Apple and T-Mobile for over 4 hours in total. I was bounced back and forth between Apple and T-Mobile, but now Apple has take on full responsibility and escalated to engineering. They said they had a fix and to wait 24-48 hours. I waited longer and it appeared to be fixed, then 48 hours later the dreaded "Activation unsuccessful" reappeared. Apple Support wants to setup another call.

Like others on here, I am on T-Mobile eSIM. I am going to pass this thread along to Apple Support.

I'd prefer to not have a physical SIM as I travel internationally and there are times I need a pre-paid SIM for data. So has anyone re-provisioned with eSIM have this fixed permanently?

Thank you again for posting this information. I did the same to have my eSIM "reset" and Activation of iMessage worked almost immediately.

I won't claim victory for the next 48 hours but things are looking good.

I will say that T-Mobile was a pain. I got bounced to three different agents as they needed a "Tech Expert" to do this.

I haven’t as of yet, the only way I personally resolved the iMessage/FaceTime issue to reset the phone. Please take caution doing this and make sure you back up everything before hand.

I have had this issue on and off since March 20th I think around the time of 15.4. I have tried all of the things mentioned beyond resetting my e-sim. I got on with a T-Mobile 2nd level support person and they mailed me a physical sim which just showed up April 13th. But since me ordering that and it showing ~April 11th/12th it seems to be that the problem no longer happens. I want to think that they solved some underlying issue but it would be good to get confirmation on this. One thing I noticed on my AppleID the phone number would keep dropping and I would have to add it back. Then when iMessage would work it would show 2 phone numbers one with iMessage/FaceTime and then one without but both numbers were the same. In the past few days it’s only showing one number under my AppleID settings and it shows iMessage and FaceTime there. So there clearly has been some change just hope we can get some confirmation so we can stop being in limbo. Attaching a screenshot but hid the phone number but know that they are the same.

I got a call from apple today and they said it’s been sent to the tech team.. one other thing they got me to do was send ‘HELP’ to 48369 but that text failed I’m in the UK so I’m not sure it would be the same number to text?

This IOS software bug doesn't seem to be related to the brief system outage.

This IOS software bug has been going on ever since I updated my phone about a week ago. This brief outage was resolved. But the bugs and being unable to activate iMessage again persists.

I was having the same issues since update to iOS 15.4 and I am also on T-Mobile with eSIM. What I did notice is when my bubbles turn green, i go to iMessage within settings and the spinning wheel was stuck next to my phone number. Exiting messages app and opening it again was fixing everything. Since around 4/10 I haven’t seen those issues again, maybe it was really something with T-Mobile eSIM and they just fixed it?

I have the same issue. As soon as the IOS 15.4 finished, IMessage stopped working with my phone number. Tried everything.

reseting the phone and restore from the backup, tried turning iMessage and FaceTime off and back on, airplane mode, restarting the phone multiple times.

it either gets stuck on waiting for activation or shows the error that is was not successful.

I’m having the same issue I’ve spoken to apple and they are telling me to wait 24 hours. I’ve tried Everything stated above. Hopefully it gets resolved soon. Was working fine until the IOS 15.4 update.