Cannot install Mojave because of lack of space

I have a late 2013 iMac with a 1TB HDD. We use a A 256gb USB SSD drive as the boot drive. However when we try to install Mojave it gives a space error. It says "the target disk is too small for this operation. Quit the installer to restart your computer and try again"

However the SSD drive has 155GB free

Yet ... if look in storage in About this mac it says the SSD drive is full (right image), yet if I "get info" from the Finder it says there is 155GB free (see left image)

The only item which is 150GB on my computer is the photos library but if I look in photos / preferences it says the library is located in the iMac HDD

And when I look at the size of each folder in the SSD it shows there is only about 100GB used and therefore 150GB free.

So ... my guess is there is 155GB free on the SSD but for some reason some parts of the system think it is full with photos so when I try to update the OS it gives the error.

The problem started with the last OS update before that it was fine and we currently run 10.13.5

How can I solve this issue? Thanks

Posted on Sep 28, 2018 2:17 PM

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25 replies

askbarnabas

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Sep 29, 2018 2:37 PM in response to macjack

I think I will. Thanks.

macjack

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Sep 30, 2018 5:29 AM in response to richardmclarke

What brand is the destination external drive? Also, what happens when the other external drive (2TB) is disconnected during installation?

Sep 30, 2018 5:36 AM in response to macjack

It's a Western Digital My Passport.

I've disconnected all other USB devices including the external drives for the updates. So, unfortunately it makes no difference.

macjack

Level 10

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Sep 30, 2018 6:53 AM in response to richardmclarke

richardmclarke wrote:

It's a Western Digital My Passport.

Do you have another drive you can test with?

Sep 30, 2018 7:17 AM in response to macjack

Unfortunately not

MrHoffman

Level 10

146,557 points

Sep 30, 2018 2:23 PM in response to richardmclarke

Complete guess: maybe https://swissmacuser.ch/macos-highsierra-apsf-issue-external-drive-not-bootable/ helps?

Oct 3, 2018 3:18 AM in response to MrHoffman

OK, so the SSD isn't apsf. However I don't seem to be able to change it. How can I change the drive to the apsf file system?

dialabrain

Level 10

136,127 points

Oct 3, 2018 5:18 AM in response to richardmclarke

Welcome.

Sep 30, 2018 12:58 PM in response to turingtest2

Thanks for everyone's help ...

I don't use the WD software, I never have done - I reformatted the drive when I got it a year ago.

No luck with the Photos system library solution either.

I don't know if this is relevant but it started before the Mojave update with the final High Sierra update a couple of weeks ago ...

If anyone has any other oddball suggestions let me know otherwise I'll just do a clean install

Oct 3, 2018 5:15 AM in response to dialabrain

Thanks. I think I'll do a clean install.

Thanks for everyone's help 🙂

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Cannot install Mojave because of lack of space