How do I fix the tab “Access Control” not opening in Keychain Access? In Keychain Access, I have some items where I cannot open the tab “Access Control”. When I double-click one of these items to open a window on it, the window opens with the tab “Attributes” selected; when I try to click the tab header “Access Control”, the header animates but the tab itself does not open. The tab “Attributes” remains selected.

I am not sure whether it’s related, but in Console I see repeated entries for Keychain Access that say: CSSM Exception: -2147413737 CSSMERR_DL_DATASTORE_DOESNOT_EXIST. There are also a lot of entries that say: CSSM Exception: -2147413750 CSSMERR_DL_INVALID_FIELD_NAME.

How can I fix the items so I can open the tab “Access Control” again? I am not sure whether the keychain itself is broken, is there some Terminal command I can use to verify (and repair) it? Or does “Access Control” rely on some other data store that may need repair?
Try setting category to "My Certificates" at the left bottom of "KeyChain Access" window. Then find the certificate, expend it to get the key and try changing "Access Control" on that one.