Lawrence Lessig, Harvard professor Wikimedia, CC One of Apple's most notable fans tells a horror story of upgrading to Apple's new software.

Renowned Harvard professor Lawrence Lessig wrote on his blog. "I live on the Apple platform" so when new versions of iOS, the Mavericks operating system and iWork arrived, "Stupidly (really, inexcusably stupid), I upgraded immediately. Every Apple-related product I use has been crippled in important ways."

For instance, the iOS upgrade broke the WiFi on his iPhone. After spending hours on tech forums, he called Apple's tech support who said the only way to fix his phone, less than a year old, was to send him a new one.

He wrote:

Because I was within the 1 year limited warranty, that replacement would be for free. Had it been beyond one year, and I didn’t have an AppleCare contract, it would not have been free. ... I would have been quite unhappy to have been told that an “upgrade” from Apple had broken my iPhone, but that I had to pay $199 to fix it.

And he's not alone. When it comes to the iWork upgrade, there have been over 150 posts to an Apple forum called "List of deleted features in Keynote '13." Users say the new version of the software breaks presentations created with the old version.

Pages users posted similar complaints on the tech support forums.

The outcry from users, spurred in part by Lessig's blog post blasting Apple, prompted Apple to admit that the new iWork wasn't compatible with the old.

It promised to fix things over the next six months:

In rewriting these applications, some features from iWork ’09 were not available for the initial release. We plan to reintroduce some of these features in the next few releases and will continue to add brand new features on an ongoing basis.

Lessig is happy that Apple finally told users about its plans. But he made a valid point: Apple could have warned them about the compatibility issues before users upgraded.

We reached out to Apple and asked for further comment.