You may have experienced the following behavior while trying to upgrade your vCenter Server Appliance (VCSA) to 6.7.x – after submitting the IP and credentials information of the current vCenter and host, the wizard end up with error without any details.
However, after downloading the log (there is a link within the red error bubble that allow you to do so, otherwise you can look under the following path : C:\Users\%user\AppData\Local\Temp\vcsaUiInstaller), you will notice the following entries in the last lines :
info: Password not expired
error: sourcePrecheck: error in getting source Info: ServerFaultCode: A general system error occurred: vix error codes = (1, 4294967286).
As counter intuitive it may be, the log indicate that the password isn’t expired, however the error code is related to either an expired password or a password near the expiration date.
Just like in this case, the password was near expiration, so I went ahead defining a new password by logging to the Platform Service Controller (https://vcenter-hostname.domain.tld/psc) and defined a new one (see the SSO section).
The error should now go away after taking this step.