coppio
Level 1 (0 points)

Q: El Capitan Installation Problem: "An error has occurred while preparing the installation. Try running the application again."

I've been on a struggle for 2 days now trying to upgrade my late 2009 21.5 iMac from Mavericks to El Capitan but as the installation is about to be initiated I get this message "An error has occurred while preparing the installation. Try running the application again".

 

Here's a list of all things I've tried:

Running the application again;

Moving the installation app to another folder;

Checking date & time and it was already correct;

Doing the installation in safe mode;

Installing the upgrade from another user that I created solely for this;

Restarting the computer and tried installing the upgrade again multiple times;

And, to be sure that the installation app was not corrupted I made a copy of it on an external HD and tried installing it on my 2011 MacBook Air and it worked (I didn't proceed with the installation because I already have El Capitan installed on my MacBook).


Well, I don't know what else can be done and I would prefer not having to completely restore my iMac.

iMac, OS X Mavericks (10.9.5)

Posted on Dec 2, 2015 8:12 AM

by Linc Davis,Solvedanswer
Linc Davis Linc Davis
Level 10 (207,963 points)
Applications
A:

Please try the installation again after taking each of the following steps that you haven't already taken.

Step 1

Reset your computer’s PRAM.

Step 2

If possible, set the system clock as instructed here. If you can only start up in Recovery mode, see below.

In the OS X Utilities screen, select Get Help Online. Safari will launch. While in Recovery, you'll have no access to your bookmarks or history. Load this web page.

Triple-click anywhere in the line below to select it:

date 0801000014

Copy the selected text to the Clipboard by pressing the key combination command-C.

Quit Safari. You'll be returned to the OS X Utilities screen.

Select

          Utilities ▹ Terminal

from the menu bar. A Terminal window will open. Paste into the window by pressing the key combination command-V.

Wait for a new line ending in a dollar sign ($) to appear below what you entered. If it doesn't appear, press return.

Quit Terminal to return to the main screen.

Step 3

If your model has user-replaceable memory, and you've upgraded the memory modules, reinstall the original memory and see whether there's any improvement. Be careful not to touch the gold contacts. Clean them with a mild solvent such as rubbing alcohol. Aftermarket memory must exactly match the technical specifications of the machine. Don't install more memory than the specified maximum, even if a RAM vendor, or anyone else, tells you that it will work.

Step 4

Back up all data to at least two different storage devices, if you haven't already done so. One backup is not enough to be safe. The backups can be made with Time Machine or with Disk Utility. Preferably both.

Erase and install OS X. This operation will destroy all data on the startup volume, so you had be better be sure of the backups.

Posted on Dec 2, 2015 12:05 PM

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coppio

Q: El Capitan Installation Problem: "An error has occurred while preparing the installation. Try running the application again."

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  • Helpful answers

  • by Linc Davis,Solvedanswer

    Linc Davis Linc Davis Dec 2, 2015 12:05 PM in response to coppio
    Level 10 (207,963 points)
    Applications
    Dec 2, 2015 12:05 PM in response to coppio

    Please try the installation again after taking each of the following steps that you haven't already taken.

    Step 1

    Reset your computer’s PRAM.

    Step 2

    If possible, set the system clock as instructed here. If you can only start up in Recovery mode, see below.

    In the OS X Utilities screen, select Get Help Online. Safari will launch. While in Recovery, you'll have no access to your bookmarks or history. Load this web page.

    Triple-click anywhere in the line below to select it:

    date 0801000014

    Copy the selected text to the Clipboard by pressing the key combination command-C.

    Quit Safari. You'll be returned to the OS X Utilities screen.

    Select

              Utilities ▹ Terminal

    from the menu bar. A Terminal window will open. Paste into the window by pressing the key combination command-V.

    Wait for a new line ending in a dollar sign ($) to appear below what you entered. If it doesn't appear, press return.

    Quit Terminal to return to the main screen.

    Step 3

    If your model has user-replaceable memory, and you've upgraded the memory modules, reinstall the original memory and see whether there's any improvement. Be careful not to touch the gold contacts. Clean them with a mild solvent such as rubbing alcohol. Aftermarket memory must exactly match the technical specifications of the machine. Don't install more memory than the specified maximum, even if a RAM vendor, or anyone else, tells you that it will work.

    Step 4

    Back up all data to at least two different storage devices, if you haven't already done so. One backup is not enough to be safe. The backups can be made with Time Machine or with Disk Utility. Preferably both.

    Erase and install OS X. This operation will destroy all data on the startup volume, so you had be better be sure of the backups.

  • by coppio,

    coppio coppio Dec 2, 2015 12:05 PM in response to Linc Davis
    Level 1 (0 points)
    Dec 2, 2015 12:05 PM in response to Linc Davis

    Resetting the PRAM did the trick!

    I didn't think something so simple would do it.

    Thank you very much!