I got the “Openx M2M authentication error password invalid code 823” & I realise that many openx.org ad server users comes across this message when they login to their administration after an upgrade.
The reason it comes up is that you most propable have had multiple installations of the openx on your domain/server.
To fix this issue you need to login as an administrator and paste this in your browser field:
Just change the mydomain.com to your own domain/subdomain.
This way the script regenerates a new hash key and you’ll get rid of the annoying message when logging into the openx admin area.