MacOS – iPhoto problem after upgrading to Mountain Lion

Though this is from 2010, I think that it will work:

You need to re-install iPhoto because it's missing parts of itself:

To re-install iPhoto

1. Put the iPhoto.app in the trash (Drag it from your Applications Folder to the trash)
2. Go to HD/Library/Receipts and remove any pkg file there with iPhoto in the name. On 10.6 those receipts may be found in the Finder using the Go menu and selecting Go To Folder

In the resulting window type

/var/db/receipts/

1. Re-install.

If you purchased an iLife Disk, then iPhoto is on it.

If iPhoto was installed on your Mac when you go it then it’s on the System Restore disks that came with your Mac. Insert the first one and opt to ‘Install Bundled Applications Only.

Source: https://discussions.apple.com/thread/2658126?threadID=2658126

I've had never any problems with upgrades and never lost any files.

You should make a backup — or better, make a bootable clone of your current hard drive:

• Buy an external hard drive
• Install Snow Leopard on the external drive.
• Reboot into the clean external Snow Leopard drive, migrate over users and apps and run all updates. Run from that external to be sure it's a workable copy of your internal drive.
• Disconnect the external drive and put it on the shelf.
• Reboot back into your regular internal hard drive and proceed with the upgrade to Lion.
• Download Lion and run the installer!

Until you're certain that Lion works perfectly, keep the clone around - several months is usually enough time. If you ever need any files from it, just attach the drive and drag-and-drop them. If something goes really horribly wrong, you can boot into the clone, and then clone it back to the internal drive (you'll lose any changes made since you installed Lion). This second drive is really valuable for when you discover three months down the road that one seldom used piece of software won't work on Lion. You can reboot into Snow Leopard where everything still works and get that one task done. It's a great lifesaver and means you can start using Lion rather than checking that every little thing works perfectly right after the upgrade.

EDIT: Thanks Trombone for editing my broken-english post, but please, never add your own ideas into my post. My solution uses pure apple tools, so why bother with SuperDuper, when you can do it with nice clean install and Migration Assistant.

I never recommend any third-party products when things can be done with default Apple SW. Of course, you can prefer SuperDuper, it is your way - but not mine. Please add another answer explaining how to use SuperDuper or other awesome tools so that people can have a choice. Let's keep this solution needing no additional tools.