FYI
Just updated from 6.8.9 to 6.8.10 and had old problem see http://forums.b2evolution.net/auto-upgrade-failure-6-8-8-to-6
Waited a few more minutes etc tried [Update database] no luck, same old, can't find [Install] folder but does exist according to Filezilla :)

renamed umaintenance.html and all ok

deleted [install] folder

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