I just picked up a MacBook Pro 2008 model and installed Mountain Lion. Everything appeared to be working okay so I upgraded to El Capitan to see how that looked. After the update, trying to login to iTunes or the App Store resulted in the spinning ball of uselessness. However, I was still able to login to Apple’s web site via Safari and Firefox, so I figured networking and firewall were non-issues.

Some research on Google directed and redirected until I ended up at http://rogersm.net/icloud-problems-mountain-lion-serial-number. Turns out this can be a common problem with machines that have been serviced, which can apparently wipe out the serial number stored in the firmware. The solution listed on that site worked like a charm. You can verify this is the problem by clicking on About This Mac from the Apple menu; if your serial number is blank or otherwise appears unavailable, you might give the utility a shot.

A couple of additional notes, however. For those that aren’t really Mac savvy or have been away a while, Disk Utility will work fine for this and can create the serial number utility on a USB memory stick. To accomplish this, start Disk Utility from Applications -> Utilities. Insert your memory stick and if any partitions mount, select the in the list and unmount them (don’t eject the memory stick). Once all partitions of the memory stick are unmounted, click on the memory stick itself and then Edit -> Restore. In the window that pops up, click Image and select the .dmg file described in the above article. Once everything is completed, you can reboot and try the serial number utility. Make sure you read the article completely, however, and that you absolutely use the correct serial number. There is no second chance…