I cannot purchase any app from the AppStore because I get the "INSTALL ERROR DISTRIBUTION SIGNED BY APPLE" notice.

Frustrating - cannot purchase from the AppStore.

Back up all data.
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. Click Utilities, then Keychain Access in the icon grid.
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 toCRL. Log out, log back in, and test.

Similar Messages

Maybe you are looking for