Running OS X Yosemite, but About This Mac shows Version 10.90

Solution 1:

Download the latest Yosemite installer from the Mac App Store but do not install it.

Copy following in to your Terminal to verify the downloaded Yosemite file is correct:

shasum /Applications/Install\ OS\ X\ Yosemite.app/Contents/SharedSupport/InstallESD.dmg

Wait for a minute for it to calculate. The result for the previous version should be:

eebf02a20ac27665a966957eec6f5e6fe3228a19  /Applications/Install OS X Yosemite.app/Contents/SharedSupport/InstallESD.dmg

And for Yosemite Download as of Nov. 27 the result is:

a673c2c6d967f4da2934b7d6cf3736936970b194  /Applications/Install OS X Yosemite.app/Contents/SharedSupport/InstallESD.dmg

Proceed with Install.

Solution 2:

Mmmh, maybe you've changed it yourself and forgotten about it?

Changing OS X version to 10.90 has been suggested to solve some compatibility issues, e.g. with Matlab (see MATLab crashes on launch OS X Yosemite).

To change it back to 10.10, type the following in a Terminal window:

sudo nano /System/Library/CoreServices/SystemVersion.plist

then change the value under 'ProductVersion' to 10.10 or whatever version you fancy.