When updating with prosilver_se one gets the General Error "The file ./../styles/prosilver_se/template/bbcode.html is missing".
As per the report in http://area51.phpbb.com/phpBB/viewtopic.php?f=3&t=42999 it seems like the problem occurs when running the updater most likely because of changes to the inherit metadata in style config files in 3.0.11.
"Hmm, this is weird. It should not update prosilver_se at all. Is this error during the file update step or right when you start the update?"
> "To perform the update I had to install prosilver and make it my default style on the forum."