I've not been able to upgrade to 9.1R8 from 9.1R7, but it worked after rolling back to 9.1R6 and then upgrading to 9.1R8. HOWEVER, I DO NOT RECOMMEND UPGRADING TO R8 RIGHT NOW. There is an extremely bad time server bug that, if not checked every few hours, risks completely breaking connectivity. What happens is that the clock skews into the future at a rate of around 2hrs+ every 12hrs. If you do not make sure it doesn't skew too much or if you don't change the "allowed clock skew" of your auth servers, your logins will fail. They said R8.1 would be released last week but nothing yet.
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