iPhone SE 3: iOS 17 to 18 update questions

Yes, option 1 should be what happens if iOS 18 is being offered in Software Update.

Also, you’ll inevitably have to update to 26 at sometime, so you might as well rip the bandaid off and do it.

If you don’t have enough space on device, you can update using a computer, but I don’t know if it will offer iOS 18 though.

click here ➜ Update your iPhone, iPad, or iPod touch with the Finder - Apple Support

or here ➜ Update software on iPhone, iPad, or iPod touch in iTunes on PC - Apple Support

My guess is Ootion 1.

When Apple released iOS 18.7.3, they took away the option to update to it for any iPhone capable of running iOS 26. That left updating to iOS 26 as the only way to get the patch to keep iMessages working on those phones.

Later, after I had updated my iPhone to iOS 26, Apple apparently relented and started offering iOS 18 updates to phones that were compatible with iOS 26, but not on it yet. This was very unusual- normally when Apple stops signing releases, they never reverse the decision.

just wanted to be sure by asking around, maybe someone else had the same situation as me.

Most of these situations occurred almost a year ago. I can remember users posting that they were able to update to the latest version of iOS 18 and other users posting to ask why if they were given the option to update to iOS 18 that iOS 26 was installed instead......with no option to go back to iOS 18.

That's why my answer to your first question above was "maybe", and I noted that I would not be surprised if iOS 26 was installed on your phone even though you saw a message about updating to iOS 18.

If you are not prepared for the possibility that iOS 26 may be installed, then it would probably be best to hold off for now.

My question is... if I make space and try to download 18.7.8, is it going to:

1) Download and update my iPhone from 17.6.1 to 18.7.8

Maybe, but normally if an iPhone is eligible for iOS 26.....the SE3 is.....that is what will be installed. Things were really confusing at the time, and a rare exception was made. I don't know if that exception still holds.

If your SE3 has plenty of space, it would not surprise me if iOS 26 was downloaded.

2) Download the update but tell me it can't continue because I'm running iOS 17

No

3) Download the update [18.7.8] but tell me it can't continue because I'm running iOS 17

No

Regarding your question about updating the iMac, i don't have an iMac here to run some checks.

Bob Timmons wrote:

just wanted to be sure by asking around, maybe someone else had the same situation as me.

Most of these situations occurred almost a year ago. I can remember users posting that they were able to update to the latest version of iOS 18 and other users posting to ask why if they were given the option to update to iOS 18 that iOS 26 was installed instead......with no option to go back to iOS 18.

That's why my answer to your first question above was "maybe", and I noted that I would not be surprised if iOS 26 was installed on your phone even though you saw a message about updating to iOS 18.

There's another thing to watch out for. These days, when you install an iOS update on your phone, that turns automatic updates on – even if you had intentionally shut those off.

So if you did update an iPhone SE 3 from iOS 17 to 18, and you didn't notice that change, the phone might then automatically update to iOS 26 one night without so much as a "by your leave". After which you would not have any option to downgrade iOS.

If you really want to control when updates are installed, these days, you need to be ready to turn the switch back off after each and every update that you manually approve …

LD150 wrote:

No, ios26 is your only option.

The OP reports that their iPhone is offering a choice of iOS 18 or iOS 26.

If you find ios18 on the internet it is unofficial and possibly dangerous

The OP is not asking about "jailbreaking" an iPhone and downloading some random file from the Internet. They're asking about whether a choice that Software Update is offering is "for real".

LRD wrote:

On a side note, I find 17.66 GB a lot for an iPhone update. Currently, Apple offers me an update for my iMac from 15.7.7 to 26.5.2 for "only" 10.05 GB. What gives?!

I don't know, but it seems quite possible that the Tahoe update is a "staged" one that involves multiple rounds of downloading stuff from the Internet, and that should any round fail, the whole update might fail.

Apple might be trying to do iPhone updates in a way where everything needed to do the update gets downloaded "up front", to reduce the chances that an interruption in Internet connectivity could result in a partially updated OS and an unusable device.

Servant of Cats wrote:

LD150 wrote:

No, ios26 is your only option.

The OP reports that their iPhone is offering a choice of iOS 18 or iOS 26.

I continue to learn, never known that option to happen before at this stage.

Maybe should have said only sensible option.

Every single case of anyone trying to go from a 2 year old OS to a one year old OS in all the years I have been here have been impossible.

If you can still do it, good luck to you.

Nothing in your question persuaded me that you were anything different and must be mistaken somewhere .

Please post your screen shot of your Settings, General, About page cropping off the serial number.

Yes 17.6 GB is too much for an SE, another clue,

The fact you can't manage space properly is another clue.

My SE runs ios26 perfectly, it will run 27, I have 18000 photos and videos all in 45 GB total storage.

Running the latest OS means I am protected from Pegasus and Dark Sword.

If you need more help with storage or security ask and someone will possibly help.

LRD wrote:

I was very polite with my answer.

And it is a fact you didn't read my post correctly because you are the one who insinuated I was trying to install iOS 18 illegally.

Still awaiting the screen shot, otherwise I conclude you are totally mistaken about being on ios17 and case closed

My phone is on 17.6.1 - I need to update it to update an app I want to use. I have an option to update to 18.7.8 and to 26.6. Why does my say, “iPhone an update has been downloading automatically. Choosing to download this update will delete the existing update.” When I go to update my phone to 18.7.8, it says it’s temporary unavailable. I have storage, and I have battery.

Re: “When I go to update my phone to 18.7.8, it says it’s temporary unavailable”

Which probably means exactly what it says - that it is temporarily unavailable from Apple’s servers and you should wait and try again later.

Unless, perhaps, Apple has changed their minds again and decided that anyone whose phone can run iOS 26 will not be offered iOS 18. If they have done that, thrrr would not be anything you could do about it.

Colestan11 wrote:

My phone is on 17.6.1 - I need to update it to update an app I want to use. I have an option to update to 18.7.8 and to 26.6. Why does my say, “iPhone an update has been downloading automatically. Choosing to download this update will delete the existing update.” When I go to update my phone to 18.7.8, it says it’s temporary unavailable. I have storage, and I have battery.

grasp the nettle, update to 26.6

Colestan11 wrote:

My phone is on 17.6.1 - I need to update it to update an app I want to use. I have an option to update to 18.7.8 and to 26.6. Why does my say, “iPhone an update has been downloading automatically. Choosing to download this update will delete the existing update.” When I go to update my phone to 18.7.8, it says it’s temporary unavailable. I have storage, and I have battery.

It's probably already downloading iOS 26, which means when trying to download iOS 18, it needs to stop the iOS 26 download delete the download and start over with iOS 18.

With that said, iOS 18.7.8 is no longer available as it has been replaced by iOS 18.7.9, so either the window to still update to iOS 18 has passed, or you need to refresh the Software update page by closing out of Settings and going back in to get the new version if it still allowed to update to a version of iOS 18 instead of 26.

Otherwise as has been suggested, just update to iOS 26.