Two days after release of vSphere 5.5 i have tried the upgrade of our vCenter and it was not a “Next-Next-Finish” thing.
During the upgrade of the SSO service a rollback happens and the only thing i found in the logfiles was a cryptic error 1603.
After a longer search i found a thread in the VMTN forums Error Upgrading vCenter Single Sign-on to 5.5 and one post directed me in the right direction.
One key in the windows registry was empty: HKLM\SOFTWARE\VMware, Inc.\VMware Infrastructure\SSOServer\FqdnIp
After i filled this key with the FQDN of our server, the install work flawlessly.