Q: Trying to upgrade to Yosemite

Hi All,

So, I was trying to update my older iMac (OS 10.9.5, 2.66 GHz Intel Core 2 Duo; 3GB 800 MHz DDR2 SDRAM) to Yosemite, and after one of the reboots it started asking for keychain passwords!? I don't know how to stop it from asking, and it seems that all the passwords I try(that I know off) are not accepted. I cancelled out of it and returned to the desktop, except that it is STILL asking for these passwords!? The 3rd one is asking for is called: "Messenger agent" and wants to use the "Local Items" keychain!?

HELP Please. TIA.

See images below: