After updating my Xcode, I noticed that plugins got disabled. To reenable them, the easiest way is just “touching” all the plugin directories:
$ cd ~/Library/Application\ Support/Developer/Shared/Xcode/Plug-ins $ touch *
After that, restart Xcode and you will get a dialog asking if plugins should be loaded.
An alternate take on this is can be found here: Re-enable Alcatraz on Xcode 6.3.2 or Newer
Additional tip: if the update was the OS, maybe this StackOverflow answer can be also useful: CocoaPods doesn’t work after upgrading Mac OS X EI Capitain.
$ defaults delete com.apple.dt.xcodebuild DVTPlugInManagerNonApplePlugIns-xcodebuild-7.3 $ defaults delete com.apple.dt.Xcode DVTPlugInManagerNonApplePlugIns-Xcode-7.3
Additionally, I guess that some plugins need an update, because they are not working (for example CocoaPods).