Back up all data, then test after each of the following steps that you haven't already tried. Stop when the problem is resolved.
1. Press the down-arrow key. (Credit to ASC member iNeight.)
2. Quit and relaunch Safari. Force quit if necessary.
3. Click in the first field to be filled, and then select
Edit â–¹ AutoFill Form
from the menu bar. You may have to reload the page in order to do this.
4. Select
Contacts â–¹ Preferences â–¹ vCard
and uncheck the box marked
Enable private me card
if it's checked.
5. Select your card in Contacts. Then select
Card â–¹ Make This My Card
from the menu bar.
6. In Safari, select
Safari â–¹ Preferences â–¹ AutoFill â–¹ AutoFill web forms: Using info from my Contacts card
If the box was already checked, uncheck it and then check it again.
7. 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.
Select the login keychain from the list on the left side of the Keychain Access window. If your default keychain has a different name, select that.
If the lock icon in the top left corner of the window shows that the keychain is locked, click to unlock it. You'll be prompted for the keychain password, which is the same as your login password, unless you've changed it.
Right-click or control-click the login entry in the list. From the menu that pops up, select Change Settings for Keychain "login". In the sheet that opens, uncheck both boxes, if not already unchecked.
From the menu bar, select
Keychain Access â–¹ Preferences â–¹ First Aid
If the box marked Keep login keychain unlocked is not checked, check it.
Select
Keychain Access â–¹ Keychain First Aid
from the menu bar and repair the keychain. Quit Keychain Access.
8. Run Software Update and install any available updates.
