Understanding “iPhone is synced with another iTunes Library. Do you want to erase this iPhone and sync with this iTunes Library” Message

Nov 1, 2015 - 20 Comments

Device synced with another iTunes library, erase and sync? What does this mean and do?

One of the most frightening iTunes messages an iPhone, iPad, or iPod user may see when they connect a device to a computer is the “The iPhone (Name) is synced with another iTunes Library on (Computer). Do you want to erase this iPhone and sync with this iTunes Library?” message, which gives you two options, to Cancel, or to “Erase and Sync” – this sounds like you’re about to erase everything on the iPhone or iPod touch completely, right? Well, it doesn’t quite work like that.

Let’s examine this iTunes alert message and understand what it means and what the resulting “Erase and Sync” action actually does.


In case there’s any uncertainty, the complete iTunes message you’ll see is this:

“The iPhone (Name) is synced with another iTunes Library on (Computer). Do you want to erase this iPhone and sync with this iTunes Library?

An iPhone can be synced with only one iTunes library at a time. Erasing and syncing replaces the contents of this iPhone with the contents of this iTunes library.”

Obviously we’re focusing on iPhone, but you can replace iPhone with iPod touch or iPad, assuming those are the devices in use.

What it sounds like: Erase everything on the entire device

The message is intimidating and it sounds as if you press “Erase and Sync” that your entire iPhone, iPad, or iPod touch is going to be erased, right? Yes that is how it reads and how it sounds, which makes this a terrifying message to see in iTunes… but the good news is that basically this is the most poorly worded iTunes message you’ll ever see because clicking “Erase and Sync” does not actually erase the iPhone at all, it just removes the iTunes content from that iPhone. The extended dialog text sort of hints at that, but it’s really not clear enough, and the button is “Erase”, which likely inspires a million backups.

Does that make sense? If you click on “Erase and Sync”, only the iTunes content on the device will be removed and erased, not anything else on the device.

What it actually does: Erase the iTunes media only, nothing else is erased

For example, if you have a large music library on the iPhone and click on the Erase and Sync button, that music library will instantly vanish, but all of your contacts, photos, apps, customizations, and other media remains untouched on the iPhone. Only the music and iTunes content will disappear. That means the entire large music library will vanish, but nothing else will.

For example, here’s what happens if you connect an iPhone into a new computer that has been synced with a different computer:

Erase iPhone and sync with iTunes library or not iTunes message

Clicking on the terrifying “Erase and Sync” button will remove the music library and iTunes content, but nothing else, as seen in the storage bar of iTunes for this device:

Erase and Sync just removes the iTunes content, nothing else

As you can see in the screen shots, there are many GB of photos and other data on the device, none of which has been touched despite clicking the dreaded “Erase and Sync” button. Once again, only iTunes related media from the old iTunes library is removed. That means if you had a bunch of songs from an old computer on this device, they’ll be removed. One way around that scenario is to copy the music from the iPhone, iPod, or iPad to the computer first using a third party tool, importing that library into iTunes, then using the “Erase and Sync” option as outlined above. Another option is to copy sync data to be able to sync iTunes without losing anything.

Try it yourself, you’ll get the same effect. If you’re still worried about it, which is understandable given nobody actually wants to erase all their stuff just to sync iTunes, just back up your iPhone, iPad, or iPod touch first.

You’ll see this message if you’ve ever configured an iPhone on another computer and tried to connect it to another one. You’ll also see this message if you’ve restored a new iPhone or iPad from an older backup that was once synced with another computer, then tried to connect to a different computer with iTunes.

This message has been worded this way for as long as iTunes has been syncing with devices, but it really should be clarified to not sound as frightening.

By the way, if you actually do want to reset an iPhone back to factory settings and remove everything from it, you can do that too with these instructions.

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Posted by: Paul Horowitz in iPad, iPhone, iTunes, Tips & Tricks, Troubleshooting

20 Comments

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  1. John says:

    With the last couple itunes updates I no longer get this error message. I have a pretty old ipod nano that I use–maybe five years old–and I sync it with my imac every day to update my podcasts. I never connect or sync it with another computer. Yet I still got this message randomly every couple weeks, and had to just let it erase all my playlists and go through and click the ones to sync again. It was pretty annoying. Glad it stopped. The only problem now is that the most recent itunes update, 12.3.123 is about the worst update they’ve ever had. It is painfully slow. Doing something as simple as right-clicking to mark a podcast as played gives you the spinning ball and freezes it for a good ten seconds. Even clicking a tab to move from podcasts to playlists takes several seconds. And it will not refresh and update podcasts unless you quit and restart itunes. Would love to see an OSXDaily tip on how to get the latest itunes working the way it should!

  2. Sid says:

    What happens to my iCloud music backup once I erase the iTunes data on my iPhone? When I backup the new data wouldn’t it replace the old data in my iCloud backup?

  3. Suzanne says:

    This msg was a major problem for me. I had a huge iMac at home synched to my iPhone, iPod for music and backups. I travelled with my MacBook Pro which did not have all of my music. If I added music via the MBP and then wanted to synch this to my iPhone, I had to agree to losing the music that was on my iMac but not on my MBP, just so I could add new music.

    I finally decided to downsize by getting rid of the iMac and buying a bigger MBP. Now my devices only need to synch with one iTunes.

    To the synch, Apple should offer the ability to KEEP EXISTING and ADD NEW to the devices once it verifies that what it will be keeping came from the same Apple ID.

    • plastic people says:

      The message is so poorly worded it’s a useless dialog. I bet it was rammed in there by some industry in agreement to allow their content onto iTunes.

  4. Boss says:

    Y’all didn’t add that if you have music and want to keep it but also add music from someone else’s iTunes this message will appear but you can get around it by pressing cancel then manually manage music to add the new songs. You’ll likely get the message again but since you’ve pressed manually manage the music will stay.

    • Nope says:

      It still gets rid of it, and then will even revert to not allow you to manually control it. Stupidest @#@#!%!@#!@ program ever.

  5. Anne-Michelle says:

    THANK YOU!!!!

  6. Mr Mckenzie says:

    Thank you SO much! My original back up was on my old laptop and my new back up on my new laptop. I had my phone replaced today and restored from back up but my music wouldn’t because it’s from my old iTunes. As stated the only thing it erased was my music on my phone, which there was none and started to sync my new iTunes music

  7. Laura says:

    I just uploaded songs from a CD that I own and the songs from the CD won’t automatically sync to my phone because it says I have music on an old computer we own. When you click the “erase and sync” button, does it erase the itunes library that was on the old computer or the itunes library on the new computer?

  8. Dave says:

    Did this today and worked fine, thanks very much was very worried about the “erase” message!

  9. tjejojyj says:

    Thanks. Glad I’ve finally read something cogent and sensible on this warning.
    Apple does many things well so when that trip up like this it is always a bit of a shock.

  10. paybdb says:

    Got a new ipad a few months ago. Set it up via itunes but every time I connect to my laptop to add a new movie or anything, I get this message. Completely erases everything from itunes and I have to start from scratch. Hate itunes.

  11. kosmo says:

    Thank you VERY MUCH for this clarification.

    I would like to add that, as you said, when you sync, only the music library is removed. The iBooks library is NOT removed, and then I was able to sync the iBooks from my iPhone to my Windows PC running Windows 10.

    I need to turn in my iPhone because the glass is cracked, and I really wanted to save those PDF documents. Greatly relieved that this worked.

  12. DD says:

    Man, you saved my day… Thank you.

  13. T says:

    Just wanted to leave a comment and say thank you! I even called customer service before reading this.

    Just a side note: if the photos are from an external folder (for example: a folder under the photos) those will be erased, not the ones you have *taken on your phone.*

  14. RS says:

    I did exactly as above but instead it took what was on my iPhone and replaced that with my library on my iTunes pc. I lost over 4000 songs. How do I get this back? I uploaded all my old CDs to my iTunes library. Please help!

  15. Eva says:

    I just don’t want to sync anything, I always managed my music on the iphone manually and always will. I don’t want to update iTunes either, since its user experience all the time gets worse. This is so annoying…
    Even after updating anyway to 12.4.3.1 the greyed out songs are not to be deleted.
    I also had some iCloud music that could not get erased. I discovered I had to change settings and “not show iCloud content”. So iPhone mp3s are uptodate now, just iTunes shows greyed out iPhone content.

  16. S says:

    Oh. In that case, I suppose it’s fine that I’m not allowed to add more music to my phone without deleting all the songs I already payed for, just because I had to get a new computer.
    Go to hell, iTunes.

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