Here we can see, “How to Upgrade to OS X El Capitan GM from a beta build”
Users and developers running beta builds will not be able to upgrade directly from the App Store to OS X 10.11 El Capitan GM, which Apple just released. Instead, you’ll need to pass through a few minor hoops before upgrading from an El Capitan beta build, such as seed 15A278b, to the El Capitan GM release 15A282b.
- Instead of heading to the “Updates” page (where there are none), go to the “Purchases” page in the App Store.
- If you’ve already installed an El Capitan build, you’ll see “OS X El Capitan GM Candidate” in your purchases list, along with a download button:
- Selecting “Download” will bring up a warning popup noting that you will be downloading the whole installation image rather than updating, and suggesting you to “Update” instead – unfortunately, this is not an option at the time of this writing, and you must click “Continue” to download anyway:
- Because there appears to be no delta update at this moment, the OS X App Store will begin downloading the complete picture – yep, all 6.06 GiB —:
- The installation should begin once the download is complete. If not, you can start the installation manually from the same page. Before you begin the upgrade, make a backup of your Mac.
Update: According to an email issued to beta testers by Apple, there will not be a delta update available for current beta testers:
I hope you found this information helpful. Please fill out the form below if you have any questions or comments.
1. What is the GM candidate for OS X El Capitan?
The “Golden Master” version of the OS is GM Candidate. Essentially, it is feature-complete and thoroughly tested. Sometimes the Golden Master becomes the public release; other times, minor adjustments are made, and the public release has a different build number than the GM version.
2. Is it possible to upgrade El Capitan’s operating system?
You won’t have to do anything to get it set up. However, if you wish to upgrade an existing computer, go to the App Store on your Mac and select Updates to download and install OS X El Capitan.
3. Is it possible to upgrade El Capitan to Big Sur?
Apple provides instructions for installing a terminal release of Mac OS X or macOS for its older systems. In addition, you can use Migration Assistant to transfer data to Catalina or Big Sur once you’ve upgraded to El Capitan or later.
4. The OS X El Capitan beta is really, really nice. : r/apple – Reddit
5. Installing El Capitan GM over Beta 6 fails : applehelp_betas – Reddit