When an app ran fine, but crashes in El Capitan, it may be SIP’s fault. Here is how to check, and more about SIP.
Disk Utility
When verifying my hard disk, Disk Utility reports that the ‘keys are out of order’. What do I do next?
How to repartition and install El Capitan afresh on an old iMac.
My iMac persists in starting up and freezing every morning. How can I stop it?
Why do I see several disk images in the sidebar of Disk Utility?
The new 4 TB hard disk I have just installed in my Mac Pro has become uncooperative. Has it died already?
When my external drive woke from sleep. it needed repair, but Disk Utility cannot help. What should I do?
Which apps SUID and can be ignored in Disk Utility logs?
After breaking the RAID mirror set, my Mac mini Server will not start up. Have I corrupted it?
Does a ‘bitmap error’ mean that my hard disk is about to fail?
The Eclectic Light Company 