I’m running Tiger (Mac OS 10.4.11) on my six-year-old PowerPC iMac. I want to upgrade my OS to as high as it can go and then upgrade some applications as well. I got a series of OS upgrades from apple.com/download, which I thought would take me from 10.4.11 up to 10.4.6. But unless I can get 10.4.2 installed, I have no hope of moving further. When I attempt to install 10.4.2, I get a message saying, “You can’t install Mac OS X Update on this volume. This volume does not meet the requirements for this upgrade.” Is the problem that I’m upgrading from 10.4.11 rather than 10.4.1? I don’t have 10.4.1 to go back to. Any wisdom, or am I stuck in a sinkhole?

You’re going to love this answer. Mac OS 10.4.11 is the highest version of Tiger, so your quest was accomplished before you even started. Blammo!

Tiger stopped at 10.4.11, so your only upgrade path from here is Leopard.

It seems the confusion is about version numbers. 10.4.11 doesn’t come between 10.4.1 and 10.4.2; software version numbers don’t work exactly like decimals in actual math. In math, 10.4.11 is between 10.4.1 and 10.4.2, but software versions ignore the rules of trailing decimal places and just go sequentially. Check out en.wikipedia.org/wiki/Mac_OS_X_Tiger for a list of Tiger versions and notice how 10.4.9 is followed by 10.4.10 and 10.4.11, the OS you’re running already.

So go ahead and delete those 10.4.2 through 10.4.6 updates--you’re beyond them already. Success. And also? If there really were Mac OS upgrades available for your iMac, they would’ve shown up automatically under Software Update in the Apple menu.