How to Fix the Mac ‘A required download is missing’ Error (During macOS Install)

Attempting to revive an older Mac by completely formatting the hard drive and reinstalling macOS via Internet Recovery is usually a seamless process. However, you might reach the final step of the installer only to be blocked by a frustrating pop-up message stating: “A required download is missing” or “An error occurred while preparing the installation. Try running this application again.”

This error is almost always caused by a discrepancy in the Mac’s internal hardware clock. When your Mac connects to Apple’s servers to download the massive macOS installation file, Apple’s servers check the digital certificates of the installer. If the date and time on your Mac’s motherboard are significantly out of sync with the actual global time (usually because the Mac has been turned off and unplugged for months, draining the CMOS battery), Apple’s servers reject the connection, assuming the digital certificate has expired.

How to Fix the “Required Download is Missing” Mac Error

You must use the Terminal within the Recovery Console to manually force the Mac’s hardware clock to the current date and time.

1. Click OK on the error message to return to the main “macOS Utilities” screen.
2. Look at the very top menu bar on your screen. Click on Utilities and select Terminal from the drop-down menu.
3. In the black Terminal window, you must format the current date and time into a specific numerical string: [Month][Day][Hour][Minute][Year]. (For example, November 16th, 2024 at 2:30 PM would be 1116143024).
4. Type the word date, press the Spacebar, and type your numerical string. For example: date 1116143024
5. Press Enter. The Terminal will output the date you just set, confirming the change.
6. Look at the top menu bar, click Terminal, and select Quit Terminal.

You will be returned to the macOS Utilities screen. Click on Reinstall macOS and proceed through the prompts normally. Because your Mac’s internal clock now matches reality, Apple’s servers will validate the digital certificates and allow the required installer files to download without error.