Years go by but problems remain. Trying to upgrade from 10.6 to 10.7 (Lion) I get the error in this thread
"OS X can't be installed on the disk because a recovery system can't be created
Which vectors to
http://apple.com/support/norecovery
which resolves to
http://support.apple.com/kb/HT4649
which appears to have nothing to do with the topic unless you scroll all the way to the bottom and there a link
support.apple.com/kb/TS3926
takes one to another page that appears have nothing to do with the error but what the heck, I try that (as others above have observed) and that involves slightly shrinking the main partition (only shrinking by 128MB) through Disk Utility. Disk was about 75% full. I tried shrinking 200MB and it would crunch and consider and then tell me it could not resize.
So remembering that I had seen some Software updates were suggested I went back and installed those dealing with Migration Assistantand Apple install.
I then was able to resize it down about about 300MB via Disk Utility suggestion in the tech note.
I return to Applications and click on the Upgrade-to-Lion icon and ... failed again with same error!
OK so I tried to resize things downward further. Over and over. Always failed with error that I couldn't resize the partition. So I started deleting things. Got down to about 60% free space. Still couldn't resize. Called local Mac repair store who quoted me $200 to archive, provision with Lion, and restore. No to that.
After lunch I decided to try the install one more time. And this time for unknown reasons it worked. It must have had something to do with having a lot more free space available that I thought it needed (based on the technical note). One thing the guy at the store told me (that got me to thinking about it one last time) was that you needed about 25% of the space available for the upgrade to work.