When you install SharePoint Server 2010 by using the official slipstreamed version that includes SP1 you may get an error while installing SP1 for several language packs.
“The expected version of the product was not found on the system – Error when trying to Install SharePoint Service pack”
Today I had this problem with this language packs:
Looking around the internet there was exactly the same issue described in a forum post:
(german, sorry. Try this automatic translation: http://www.microsofttranslator.com/bv.aspx?from=de&to=en&a=http://social.technet.microsoft.com/Forums/de-DE/Sharepointde/thread/3aff60b7-bab7-48be-a890-be702e9ad85a)
…but no solution.
I’ve found several hints in the internet that this is caused by using the official “SharePoint Server 2010 with SP1” setup media.
Some times later I found this site:
I tried to use the trick for the language pack SP1 installers:
This solved my issue. I was able to install the SP1 for all affected language packs. – I’m not sure this is a valid procedure for production systems.