Everyone who replaces HDD in most of iMac models faces the problem that HDD fan will start to spin at maximum speed after the replacement. This speed is about 6000-7000 RPM and the noise produced is unbearable (it happens because Apple puts special firmware in its HDDs)! What is more - you cannot just switch off the fan or put it rotating at MIN value (actually it's OK but only for SSD), because it will cause HDD overheating.

I have installed on MacMini (Early 2009) successfully.

During the process I had face off with 2 problems:

1. The patcher app wasn’t capable to download the Mojave image file…after a couple of seconds the download has canceled. So, I have to download it from elsewhere.

2. After the successfull install I have realised Mojave couldn’t connect to AppStore.

Solution:

If App Store is running, quit the app.

Open the Terminal (you can search for it using Command-Space).

Copy and paste this: defaults delete com.apple.appstore.commerce

Run the command.

Open App Store, sign in, and hit retry a few times.

1. If App Store is running, quit the app.

2. Open the Terminal (you can search for it using Command-Space).

3. Copy and paste this: defaults delete com.apple.appstore.commerce

4. Run the command.

5. Open App Store, sign in, and hit retry a few times.