How I fixed the time capsule 109 errors when using an airport extreme

I tried all the other posted solutions regarding repairing the sparsebundle file, etc and nothing worked.
However if you simply delete any keychain items you have regarding the airport extreme disk it all amazingly started to work just fine. So far its been working perfectly again with my iMac and MBpro both connecting to the same (time-capsule) backup disk on an airport extreme base-station for 2 days and counting... In fact as I'm typing it just did another flawless backup like it always used to.
It seems that something stuffed up the passwords somehow in the most recent Apple Software Update.