Expect Some OS X El Capitan Problems
There will likely be some OS X El Capitan problems that arrive with the update. Even after months of testing by Apple, the public and developers there may be combinations of hardware, software and network setups that cause problems.
We've seen four small bug fixe updates from Apple that bring us to OS X 10.11.4, and there is a OS X 10.11.5 update on the way that will likely fix other bugs. The odds are good that the community will find temporary work arounds and fixes for OS X problems.
Users in the Apple Discussion Forums can often diagnose an issue and offer a remedy that you can do at home, without going to an Apple Store or paying for support. Twitter is also a good place to look for support.
Stay calm, and look for help if you run into problems. This is one of the reasons we suggest you back up your computer and that you should set aside time for the upgrade. Use this list of common OS X El Capitan problems and fixes to solve some on your own.