“Directives AcceptMutex, LockFile, RewriteLock, SSLMutex, SSLStaplingMutex, and WatchdogMutexPath have been replaced […]”

Upgrading to 2.4 from 2.2 [apache.org]
» Directives AcceptMutex, LockFile, RewriteLock, SSLMutex, SSLStaplingMutex,
» and WatchdogMutexPath have been replaced with a single Mutex directive. You
» will need to evaluate any use of these removed directives in your 2.2
» configuration to determine if they can just be deleted or will need to be
» replaced using Mutex.

Yosemite kommt mit Apache 2.4.9 [apple.com], und nicht mehr mit 2.2 wie frühere OS X-Versionen.