Pivotal Cloud Foundry (PCF) 1.9
During upgrades from PCF 1.9, the UAA login page (https://<OPS-MAN-FQDN>/uaa/login) may appear either blank or may present an error such as "Uh oh. Something went amiss."
UAA logs (/tmp/logs/uaa.out on the Operations Manager VM) may also show errors of this kind:
Caused by: com.fasterxml.jackson.core.JsonParseException:
Unexpected character ('%' (code 37)): expected a valid value
(number, String, array, object, 'true', 'false' or 'null')
Cookies set by the previous instance of Operations Manager are not recognized by the new instance.
Clear the browser cache, in particular, all cookies. After that, you should be able to log in successfully.
Using a different browser will also work if clearing the cache is not desirable.