Alistair_XIII Said:
"Downgrade Safari: I have just downgraded from Catalina from Mojave. Everything is working well except for Safari. The version of Safari from Catalina no longer works on Mojave and it cannot be opened. I am now without a browser on my Mac. The Safari icon has a cross over it and the error message below appears when I click on it. Can anyone help me get a version of Safari back that works on my Mac? Thank you."
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Try This:
1. First, Backup your Mac, then
2. Then, install your macOS Mojave anew.
3. Finally, migrate it over.
In Depth:
Back up your Mac:
Start by Creating a Time Machine Backupof my Mac. That way I could be assured that Incan recover my Mac, should I need the App back or if anything goes wrong due to the removal. So, Create a Time Machine backup of your Mac, so that you can have something to restore your Mac from, should anything go wrong with the reinstall.
Use a USB Bootable Installer:
Create a USB Bootable Installer for Mojave. Delete the hard drive's partition. Then, install Mojave with. Go Here: How to create a bootable installer for macOS - Apple Support. Next, migrate it over from the Time Machine Backup you created in step 1 to this new install.