The OS X Yosemite v10.10.4 update improves the stability, compatibility, and security of your Mac.
• Improves networking reliability
• Improves Migration Assistant reliability
• Addresses an issue that prevented some external displays from functioning properly
• Improves the reliability of upgrading iPhoto and Aperture libraries to Photos
• Improves reliability when syncing photos and videos to iCloud Photo Library
• Addresses an issue that could cause Photos to unexpectedly quit after importing some Lecia DNG files
• Resolves an issue that could delay outgoing email messages in Mail
For enterprise customers, this update:
• Addresses an issue where OS X systems bound to directory services could stop responding under certain conditions
• Adds the ability to create mobile accounts with the createmobileaccount tool
• Fixes an issue in Profile Manager that could allow a user to install pre-release software even when the setting is disabled
For detailed information about the security content of this update, see Apple security updates.
How to update your Mac
1. You should back up your Mac before installation. To do this you can use Time Machine.
2. Use the Updates pane of the Mac App Store to check for the latest Apple software updates, including this update.
3. Other software updates available for your computer might appear, which you should install. Some updates might need to be installed before other updates appear.
4. Don’t interrupt the installation process once you’ve started to update your system.
5. You might experience unexpected results if you have third-party system software modiﬁcations installed, or if you’ve modiﬁed the operating system through other means.
You can also download the manual installer for this update. This is a useful option when you need to update multiple computers but only want to download the update once. Manual installers are available from Apple Support Downloads.