I have iMac running 10.10.5 I tried to download El Capitan and message said "failed to verify preflight file. It is not signed by apple." What does this mean and why can't I download El Capitan?
iMac (21.5-inch, Late 2013), OS X Yosemite (10.10.4)
Launch the Keychain Access application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad and start typing the name.
From the menu bar, select
Keychain Access ▹ Preferences... ▹ Certificates
There are three menus in the window. Change the selection in the top two to Best attempt, and in the bottom one to CRL. Log out, log back in, and test.
tried to download El Capitan to iMac 10.10.5. Would not download. Why?
