macOS – How to Restore OS X Keychain

If you have access to the Mac and can log on as an administrator, then 1) Empty the trash 2) Go to /users/[you]/library and put the entry for keychains in the trash (but don't empty the trash yet. 3) Log out and log back in. The login keychain password should now be the same as the password you used to access the user account. Hope this is of some help. Paul

I had the same issue, and this is how I fixed it.

http://www.umkc.edu/is/support/services/macintosh/keychain.asp

The essential message by default your Mac OS logon password is the the same as the keychain password. Each time you change your Mac OS logon password your keychain password is automatically changed.

For me, my mistake, I opened the Keychain Access.app which is located in /Applications/Utilities, and within the menu bar under "Edit" is the option to change your Keychain password. Well, in my case, not knowing that it should remain synchronized with my logon, I attempted to make it, what I thought, was 'more safe' by giving it a different password.

Big mistake. The next time I logged on and attempted to use my Mac anything which had data stored in the keychain - browsers, messages, the OS - compared my logon password and my keychain password and found them to be different. Thus all those pop-up prompts are generated.

The URL has the solution. In short:

1. Launch Keychain Access
2. In the upper left corner is a lock, if it is unlocked - good. If it shows locked, click it, and enter the password to unlock the keychain. (you may have to use your old password to unlock it, you may have to cancel one of the symptom pop ups to get the unlock dialog).
3. On the left side under the heading Keychains, there should be an item named login, click it
4. From the Edit menu in the menu bar choose 'Change Password for Keychain "login"
5. In the window that appears, the 'old' password is the 'current' keychain password' - probably something you changed intentionally and possibly recently. For the 'new' password which must be entered twice, enter the password you use for Mac OS login. This will restore the two to be the same and in sync
6. Restart your mac; those pop-ups will hopefully stop