As with previous versions of OS X, when you install OS X 10.11 ‘El Capitan’ the installer will detect any incompatible software you have on your system, and then disable it. However, by doing so OS X will not fully uninstall incompatible products, but instead only remove components that do not meet new requirements and which may cause instability if you run those programs.
Unfortunately this means that in some cases programs may still run and have every indication that they are working correctly, but will eventually experience problems as they try to call on the components that OS X has disabled.
To help you understand what programs have been affected by these changes and take steps to re-implement them, you have several resources available to you:
1. Application Icons
In most cases applications will remain in your Applications folder even if they are out of date and will not run on the current OS build. However, in cases where the app is identified by the system as not being able to run, you should see the application icon show with a no-entry (circle with a slash) symbol overlay. In these cases you can manually trash the app and then replace it if desired, or contact its developer for uninstallation procedures.
If an app is broken, it will show up in the Applications folder with a no-entry symbol over its icon. You can look into updating or removing these app versions.
2. The Disabled Software folder
This folder will appear at the root of your boot drive (ie, Macintosh HD), and will contain kernel extensions and other core components that are out of date and which may cause instability for your Mac if allowed to run. If this folder exists, open it to review its contents and determine whether you wish to reinstall a compatible version of the software, or remove them and related components (utilities, preference panes, etc.) entirely. If present, you will likely see Kernel Extension (KEXT) files show up in this folder.
3. The System Integrity Protection quarantine folder
When you upgrade to El Capitan, OS X will save system components that do not comply with its new System Integrity Protection feature in a separate quarantine folder structure, so they will still exist on your system but just not be accessible to run as they did in OS X Yosemite. The folder containing these files will be located here:
Macintosh HD > Library > SystemMigration > History > Migration-UUID > QuarantineRoot
Note that in this folder structure, the folder Migration-UUID will have a long UUID string of characters (instead of the word “UUID”) to uniquely identify this quarantine instance.
System Integration Protection will quarantine items here. In this view you can see commands installed by third-party software (such as BBEdit) have been isolated. However, in some cases you can just move these to alternative locations to still make use of them.
Open this folder to get a listing of system components that do not meet the specifications of Apple’s new System Integration Protection feature in OS X El Capitan. These may be small Terminal-based tools you downloaded and compiled manually, or installed with third-party software. In some cases they may be Apple-supplied components that are no longer used.
The folders that may show up are the following:
/private /System /sbin /bin /usr (all contents except /usr/local)
If you note any commands or tools that you regularly use, then you can copy them from here into locations that are not monitored by Apple’s System Integration Protection. For instance, I use a custom folder hierarchy command called “tree” that I had previously placed in /usr/bin, so El Capitan quarantined it. However, since I know this is a simple standalone command, I can move it into /usr/local/bin, or place it in a separate folder and add the folder’s path to my shell profile.