NOTE: The Migration Assistant was included in 1Password up until version 2.5.8. The assistant was removed in version 2.5.9 as we needed to solve an issue it was causing and we had hoped most people had already upgraded. We will be adding a better solution in the future, but in the meantime if you need to migrate your 2.4 data to the latest version, download 1Password version 2.5.8 and run the Migration Assistant. Once migrated, you can upgrade to the latest version.
1Password 2.5 made a lot of changes to the underlying keychain format used to store your confidential information. Version 2.5 uses a new keychain called 1Password, and the Migration Assistant will create this keychain for you and migrate all your data from your previous 1Passwd keychain. When you start 1Password 2.5 for the first time it will present you with the Migration Assistant screen to everything setup for 2.5.

The way it works is as follows. When 1Password 2.5 starts, it will look for the old keychain file (1Passwd.keychain) and it will also look for the new keychain file (1Password.keychain). If the new keychain exists, it will be used. If the new keychain is missing, but the old keychain file is present, then it will launch the Migration Assistant to create a new keychain and migrate your data from the old keychain.
Once the Migration Assistant finishes, 1Password will be launched and you will be ready to enjoy 2.5! You will now have two keychain files:
/Users/
The old 2.4 keychain is no longer needed, but it is recommended you keep it until you are happy with the 2.5 upgrade. Be sure to include the new 1Password.keychain file in your backup scripts, and configure it to sync with .Mac if needed.
Troubleshooting
We have had a huge number of successful migrations to the new keychain, but given the large number of 1Password users, Murphy's Law dictates not everyone will have immediate success. We have had some reports of the Migration Assistant being unable to create the new keychain. Below are the most common problems that can happen.
Keychains Folder Permissions
The new 1Password.keychain file will be created in this folder:
/Users/
Even if you are an administrator it is possible to configure this folder to not allow creation of new files. You can verify that you have write permissions by opening Finder, highlighting that folder, and pressing CMD-I to view the folder details.

Error -25295 and "Damaged" Keychains
According to the Keychain Reference, error number -25295 means "The keychain is not valid". When it happens you will see this window:

Alternatively, you may receive the message "The 1Password keychain file was found, but it appears to be damaged".
We don't fully understand why either of these errors happen, but it appears that the Mac OS X "securityd" process is in a bad state and unable to create the keychain.
To remedy this
- Check the /Users/your-user-name/Library/Keychains folder and rename 1Password.keychain file if there is one. Make sure to keep to old 1Passwd.keychain intact (note the difference in spelling).
- Restart your Mac in Safe Mode.
- After restart, open the Keychain Assistant program (in /Applications/Utilities) and run Keychain Access > Keychain First Aid to verify and repair the keychain.
- Start the 1Password application again to run the Upgrade Assistant.
Use the Latest 1Password Version
You can make sure you are using the latest version of 1Password. You can get the latest version by using the Check For Updates feature of 1Password, as shown here:

If you prefer, you can manually download version 2.5.1 from here Please note that when upgrading manually, you must quit 1Password and all open browsers before replacing the old version. The automatic update will do all this for you automatically.
Once upgrade, try re-running the Migration Assistant as described in the next step.
Re-running the Migration Assistant
If you decide to run the Migration Assistant again, you need to remove the new 1Password.keychain file so that the above procedure will happen. I never recommend to delete keychain files, so I suggest you rename the 1Password.keychain file to something like 1Password.keychain_old. Be sure to rename the new 1Password keychain:
/Users/your-user-id/Library/Keychains/1Password.keychain
Once renamed, it is a good idea to restart your Mac and run Keychain First aid again, just to be on the safe side. Now launch 1Password again and the Migration Assistant will appear.