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If you are using an older MacBook Pro mid-2012 model, you may be prompted in System Preferences to upgrade to macOS 10.15 Catalina. That update may get partially completed, but fail if your drive is not formatted as Apple File System (APFS). Some tips online mention a “Convert to APFS” option in Disk Utility. However, that option may be grayed out even if you startup from a Catalina install USB. This page describes a way to work around this problem. Note that this is fairy involved and time consuming. Some tools and technical skills will be required.

STEP #1 — Create macOS 10.15 Catalina USB

These instructions assume you have a working MacBook Pro that simply has the wrong drive format to allow an upgrade to a more current operating system.

Using your computer, follow the instructions outlined in the support document “How to create a bootable installer for macOS.” [View] You will need an empty USB flash drive with about 16GB or more.

  • NOTE: As of 14 Jun 2023, the Apple support page for creating bootable installer media is not loading.

In the instructions, you’ll see options for creating different bootable versions of macOS on USB. Choose macOS 10.15 Catalina.

However, if you have already downloaded it and attempted installation, you need not go through that process again. The installer is already on your computer. The “Install macOS _____” utility program will show up alphabetically in your list of Applications, with the version of the OS named. You won’t use the installation utility directly. Instead, you will follow the instructions to copy and paste the appropriate command in the Terminal interface, replacing the words MyVolume with the name of the USB device you have.

This part may seem a bit confusing and foreign if you’ve not performed a process like this before. For this part of the process, you need to open the Terminal program (found in Applications > Utilities), then paste in the correct command line (using command+v for paste) as described in the support document. At the end of that command line, replace MyVolume with whatever name your USB has. To make things easier, you may want to rename your USB drive to be something like “install” (without the quotes).

At the end of that command line you copied and pasted, replace MyVolume with the word install. If the process goes smoothly, the installation media will be created on your USB drive and it will be given a new name like “Install macOS Catalina.” This will all be done on the available working computer that you are using for this recovery process.

This USB will be used later on in this process.

STEP #2 — Remove Internal Drive

  1. Remove the bottom cover of your computer using a small-tip Phillips screw driver to unscrew the ten screws holding the cover in place. You may find that the PH00 tip works best. The PH0 size might not fit properly. Apple has a prescribed pattern of removal for the screws so as to evenly distribute the strain on the screws. You may wish to apply a full-turn counter clockwise to relieve tension on all screws before continuing. Place the screws on a clean dark surface where they won’t get bumped or fall off the table. Have them laid out in order in the same pattern as they were removed. There are three longer screws for the back right (if the hinge is away from you). Depending on the computer model, some of the screws will have a ‘hip’ which is a small barrel portion of the screw toward the head/top without any threads. These screws need to go back in the same holes they came from. In the model used for these instructions, there are four ‘hip’ screws used along the front edge, and there are two screws without a ‘hip’ that are used on the left and right side holes. You will notice a slight inset for all of these screws and the depth of the inset corresponds to the head and ‘hip’ (if present) for the screws.
  2. Once the bottom cover is removed, it is recommended to disconnect the battery whenever working inside any laptop computer, and be careful not to unnecessarily touch anything. The battery connector is near the battery. It is rectangular with a few wires running to it. Pulling carefully and evenly on the rectangular plug will work it out of the receptacle. The reason for removing the battery is to ensure any metal tools or jewelry don’t short out contacts on the main logic board.
  3. With the same Phillips screwdriver used to remove the bottom cover, loosen the two screws the plastic drive retaining bracket and remove the bracket. The screws are designed to remain in the bracket. Note that there are also two Phillips screws and a drive bracket near the edge of the computer, but these do not need to be removed. The drive will gently lift out once the main retainer bracket is removed.
  4. Gently lift the drive out being mindful of the fragile flat ribbon cable, and carefully remove the cable connector from the drive.
  5. Once removed, you will notice the drive has four mounting screws. These require a Torx size 6 (T6) driver tip. They may be tight. Carefully remove them.

STEP #3 — Place Drive in an Enclosure

Place the old drive into a drive dock or enclosure. An inexpensive drive enclose might be $12 to purchase. [View Example]

The enclosure would be the most useful for long-term ongoing use.

A SATA drive adapter cable would be another alternative. [View Example]

The goal is to prepare the drive to be externally readable with USB for the upcoming steps.

STEP #4 — Install New Solid State Drive

  1. Purchase a new 2.5-inch solid state drive. [View Examples]
  2. Use the drive mounting screws removed from the old drive. With the same Torx 6 (T6) driver, insert these in the new 2.5-inch solid state drive.
  3. Carefully connect the drive cable, and put the new drive in the computer using the retainer bracket removed earlier.
  4. Put the bottom cover of the computer back, with the screws being returned to their original locations. When initially screwing in the screws, do not screw them in all the way, let them be a little loose and then go around in a random pattern tightening them slightly more until they are all snug. When the screws are properly inserted in the correct holes, there should be no protruding sharp screw heads. Moving your hand over the screws will feel smooth because they are set in just below the top surface of the metal.

STEP #5 — macOS Installation

Using the bootable USB installation media created in Step #1, insert the media into an available USB port on the non-working computer with the computer turned off.

Turn on the computer while holding down the Option key. When given a choice of drive to startup with, choose the installation USB from the list. It should have the name “Install macOS Catalina.”

You may need to use the trackpad, mouse, or arrows to select the correct startup drive.

After starting, you should see a list of options.

Because you are working with a new solid state drive, you will need to use the Disk Utility to format/initialize the drive. Remember to choose the APFS option for the drive format so it will be compatible with the Catalina installation.

When done formatting, return to the options list and choose the option to reinstall the operating system.

At some point during the reinstallation process, you should be given an option to recover your data from a “From a Mac, Time Machine backup or Startup disk.” This is the Migration Assistant which can be run separately later, or during the system installation and recovery. [Learn More]

For purposes of this process, we will choose this option.

Using a USB cable, connect your old drive which should now be in an enclosure or dock.

The setup process will read your old programs, settings, and files into the newly formatted drive.

Follow the instructions to complete the process.

Note: If you are prompted to store all your files in iCloud Drive, do not choose that option. It will put too much information in the cloud and requires very fast internet speed all the time to work properly.

Concluding Steps

Whenever performing an upgrade like this one, involving moving to a new computer or new drive, you may need to activate some software programs again.