Delete iPhone firmware build?

I recently noticed that in ~/Library/iTunes (Catalina 10.15.7) I have a 4.10-GB file <iphone_4.7_P3_13.5.1_17F80_Restore.ipsw>.

From what I can tell, it’s a firmware build for my iPhone 7.

Any reason not to delete this?

Did you restore your phone’s firmware at some point? If so, it may be a leftover file from that.

If you want to restore your phone’s firmware today, you’ll get the latest version that runs on it, which will be version 14, not 13. And the Finder will automatically download it at that time.

Since Apple stops signing old firmware files a week or two after the next version is released, I don’t think you could install this image even if you wanted to. I think it’s perfectly safe to delete this file.

@Shamino, thanks for letting me know.

How can I tell if the firmware needs restoring?

Under Settings > Software Version, it says, “14.6 (18F72).”

By not being able to live with your current 14.6 version, but as David said, it’s almost certain that the 13.5.1 file is no longer signed and would fail, making it moot whether you wanted to retreat back to that iOS or not.

@Al, Thanks for the additional information. I wouldn’t want to restore to a previous version, only to make sure I am at the latest one. Would I have received an automatic notification?

To answer my own question, I see that 14.6 is the latest version

What was confusing me is the difference between the terms firmware and software. In this case, they seem to be the same thing?

Yes, all software updates to an iDevice are being referred to as firmware updates. I suspect it’s partly due to the closed garden philosophy currently in place for such items.

If your phone works, then it doesn’t need restoring.

“Restore” is Apple’s terminology for “erase everything and restore it to factory settings”. It’s generally considered a last resort when nothing else fixes a problem.

When you perform a restore, your computer will download the latest compatible firmware version and install it, erasing everything else that was on your phone. Afterward, you can restore your stuff from a backup. It is generally not possible to use this mechanism to revert to an older version of iOS, because Apple stops signing old images as new ones are released.

If you want to upgrade your phone and everything is working normally, then use use the normal update mechanism. Either using the phone’s update page (in system settings) or from your computer (via a USB cable). This is much faster than a system restore and will preserve your installed apps and data.

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Thanks for the explanation.

It may be, as you previously suggested, that I restored my phone a few years ago and had that file left over from it.

Now I understand, Al, why the face on your Mac is as it is: that angry red. My face looks like that, too.

Language is a wonderful and living thing, and humans are great at creating language.

But most crafts learned hundreds or thousands of years ago to fix a technical terminology and stick with it. Instead, us software folks are constantly gutting the meaning of perfectly good and absolutely useful terms of art (that is, jargon: “the technical terminology or characteristic idiom of specialists or workers in a particular activity or area of knowledge” – Merriam-Webster Unabridged 3 a).

Now we have two terms of art: “actually firmware, you know: old school” and “so-called firmware, like, you know, um… what Apple uses”. And we must add words to be specific. (This is not Apple. It is Us.)

We’re suffering from historical usage becoming increasingly wrong over time.

Firmware generally refers to low-level code burned into a device’s ROM (or more commonly today, flash). For small embedded devices like appliances, it contains all of the device’s software. For bigger things like computers, it usually refers to things like the BIOS/EFI/BootROM code - software that is not stored on primary storage (hard drive, SSD, etc.)

For mobile phones, the term used to be perfectly appropriate because the original mobile phones were fixed-function. They supported phone calls, texting and maybe a few basic built-in apps, but nothing else. So firmware was an appropriate term. When mobile phones started supporting apps (so-called “feature” phones), there was a distinction between the apps and the firmware (which was everything else).

But a modern smart phones and tablets are far more like computers than appliances. There is a low-level set of pre-boot software that initializes hardware, authenticates the OS and then boots the OS. Most people would call that code “firmware”. But the OS itself and the apps bundled with the OS really aren’t - no more than macOS and its bundled apps are firmware on a Mac. But phone manufacturers (not just Apple) continue to call it firmware, because that’s the term that was used back when mobile phones were far simpler devices.

All iDevice Operating System, e.g. iOS, updates are referred to as firmware updates.

So firmware is the layer between the application software and the device hardware. This is intended to enable applications to run without significant functional changes on multiple hardware versions. For example, updating iOS 14.4 to iOS 14.5 should not effect the User’s use of a particular app.

One can view this relationship as a four-layer stack where each layer depends on the layer supporting it:

  • User
  • Software (Application)
  • Firmware
  • Hardware (iDevice)
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Yet here, for example, Apple only mentions software:
“Update your iPhone, iPad, or iPod touch”

This is why I found it confusing.

This is not, by any stretch, the first time that Apple documentation has been found confusing. Howard Oakley ( has been documenting this often recently.

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