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Overcoming Roadblocks When Upgrading the Hard Drive in a Mac

Overcoming Roadblocks When Upgrading the Hard Drive in a Mac

I was contacted this week by a new client who had two old iMac’s, neither of which was starting up successfully. We arranged a time and I headed out to their place to take a look at the computers.

One of the iMac’s was a 20 inch model and the other was a 24 inch model. When attempting to start the computer, the 20 inch model was displaying a question mark symbol on a folder icon. This suggested to me a failed hard drive, which wouldn’t be surprising in a 14 year old computer. The larger iMac had actually started successfully but my clients told me that, most of the time, it would fail to do so.

I proposed that we upgrade the hard drive in the larger iMac to a Solid State Drive (SSD) to give it a new lease of life. We could have performed the same upgrade on the 20 inch model, but they only needed one of the Mac’s to be functioning. For this reason, we chose the computer with the larger screen.

I disassembled the iMac, removed the old hard drive, and replaced it with a 128 GB SSD. I then reassembled most of the computer in preparation for installation of the operating system to the new SSD. Because of the vintage of the computer, the most recent version it could support was OS X El Capitan.

The First Roadblock

I inserted a flash drive containing the installer into one of the Mac’s USB ports and then started the computer while holding down the option key. It was then that the first roadblock appeared.

I was presented with a padlock symbol and a prompt for a password. This was something I’d seen before, and it meant that the computer was being protected with a firmware password to prevent changes being made to its configuration. I asked my client if he had any idea about the password, but he knew nothing about it. I would need to circumvent the password in order to be able to install the operating system to the new SSD.

I shut the computer down and removed one of the two RAM modules which were installed. The RAM on this model is readily accessible by removing a screw to open a small compartment on the underside of the computer. I had already opened this compartment as it was necessary to do so when disassembling the computer.

I then started the iMac while holding down the four keys command, option, P and R together. This action resets the NVRAM and PRAM, clearing the password. The computer restarted with the usual chime and, after a couple more chimes, I released the keys. It was then possible to restart the iMac, holding down the option key, and select the flash drive as the boot device. From this point I was able to proceed with the installation.

The Second Roadblock

When the installation process reached the recovery mode screen, I was able to use Disk Utility to format the new SSD as macOS Extended (Journaled). I then launched the installation of OS X El Capitan which started successfully. However, after a few minutes the installation ground to a halt and I was presented with the message that no packages were eligible for install. Once again, this was a message I had seen before.

This message results from the fact that the signing certificate for the El Capitan installer is no longer valid. In other words, it’s out of date. In order to proceed with the installation, it’s necessary to ‘trick’ the installer into believing that we are actually at an earlier point in time. To do this we change the current date stored in the iMac to an older date.

I launched a Terminal window from the Utilities menu and typed the following command –

date 0101124517 <enter>

The format of the number shown is [month][day][hour][minute][year] so the command shown changes the stored time and date to be 1 January 2017 at 12:45. This change was confirmed on-screen.

I then closed the Terminal window and was able to proceed with the installation of OS X El Capitan. After completion of the installation, and connecting to the internet, the computer automatically corrected the date and time to the current date and time.


It’s not every day that you upgrade an old iMac with such an old version of the operating system as OS X El Capitan. However, the roadblocks I encountered aren’t unique to the specific iMac I was working on, or the specific version of the operating system. Any Mac can have a firmware password and the means of overcoming this differ from one model to another. As far as the issue with no packages being available to install goes, this can invariably be overcome by changing the computer’s date as described.

About Author:

I run a local computer repair business in Brisbane, Australia and I support both Apple Mac’s and PC’s. 

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