OS X Keychain Won't Stop Popping Up

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:

Launch Keychain Access
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).
On the left side under the heading Keychains, there should be an item named login, click it
From the Edit menu in the menu bar choose 'Change Password for Keychain "login"
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
Restart your mac; those pop-ups will hopefully stop

Keychain Demystified

What is it?

This is a subsystem BUILT-INTO OS X. It cannot be removed. It cannot be disabled. Every time you use a username and password and the app or OS asks you if you want to save this information, it's saved in your login.keychain file. Beyond that, depending on whom you ask the keychain is either..

An AES encrypted file with encryption based on the user's current password that saves all sorts of pertinent things like passwords, logins, certificates, and whatever else you want to throw it at.. OR A mysterious female-goddess who laughs at your keening wail of ignorance as you plead with her to no avail.

Where Is It?

The keychain for each user lives in ~/Library/Keychains/ and the primary one we're looking at is login.keychain The ~ above is UNIX nomenclature that refers to the 'current user's home directory'. So if you were user gschipp, then ~/Library/Keychains/ would mean /Users/gschipp/Library/Keychains/ This can be confusing, since there is a Library folder in the root of the drive. They keychain prompts that pop up are 99.999999999% of the time ONLY linked to the current user, and are therefore in their home directory within their Library folder.

Why Does It Do Me Like This?

Your keychain is an encrypted file. It is "closed" and "locked" when you're not logged in, but it "unlocks" and "opens" automatically when you login, so your applications can ask it cool stuff like, "what was the password for my AllThingsTchotchke.com account?". As long as you're logging in with the same password it was encrypted with, it'll unlock & open with no issues. Presuming you subscribe to the former definition above, when your password changes, the AES encrypted keychain no longer can "unlock" and "open", prompting you with a request to update the password, reset and start over, or continue only to be annoyed again later.

The Options

Note: These are part of the OS, again, built-in and immutable.

- CONTINUE

This is the "I'm too lazy to read, ask, comprehend, and/or weigh my options" button. Typically this is the reason that people complain about their keychain prompting them repeatedly.

When to use? NEVER

- RESET KEYCHAIN

This will ERASE the keychain. ERASE as in gone. Not recoverable. Not renamed. Not moved to the Trash. Straight up DELETED. The good news is that this will fix all the keychain issues and reset it to like the first time you logged in. The bad news is that all the passwords et al... gone forever.

When to use? ONLY If the user cannot remember their old password.

- UPDATE KEYCHAIN

DING! Choose me! This is the route that people should always take. This is unlocking the encrypted file and relocking it with a new password. Choosing this will immediately prompt for a password.. their OLD password, i.e., the one they were logging into the Mac before their changed their password. If that password doesn't work, then it's an older password that it's locked with. Key trying them until they are forced to go with the RESET option. This simple step will take care of 99.999999999% of all keychain "issues".

When you use? ALWAYS, unless the user doesn't remember their previous passwords.

OS X Mavericks v10.9.1: Repeated prompts to unlock "Local Items" keychain

After logging in, you are repeatedly prompted to unlock the "Local Items" keychain in multiple apps.

Note: This article is about the "Local Items" keychain, not the "Login" keychain. Please see this article for issues with "Login" keychain password.

Follow these steps to prevent prompts to unlock the Local Items keychain.

In Finder Select Go > Go to folder (⇧⌘G)
In the window that appears, type the following:

~/Library/Keychains/

Click OK.
Look for a folder with a name similar to this "A8F5E7B8-CEC1-4479-A7DF-F23CB076C8B8".
Note: Each folder has a unique number.
Move this folder to the Trash.
Immediately choose Apple Menu () > Restart… to restart your Mac.

After restarting the computer, a new folder is created in the Keychains folder with a name similar to "4B29A0BB-599D-47FC-A2D1-42B5592B130B". There is no need to repeat the steps in this article, or to delete this folder. The new folder is expected and corrects the symptom described in this article.

None of these answers worked for me and the Keychain Access kept crashing. I was able to fix it by removing the keychain manually:

Go to Library/Keychains (in Finder, go the the "Go" menu and hold down the option key, the Library folder will then show up in the list)
Move all the files from that folder to a temporary backup location (on your desktop for example)
Go to Library/Cache and delete everything (not sure if this step is required but it doesn't hurt).
Reboot

A new keychain will be created and the popups will be gone. You've also lost all your saved passwords, so this should be a last resort. I had no option though. If this still doesn't fix the problem, delete the contents from the Keychains folder and restore the backup you created, then look for another solution...