In my lab I was installing a new Exchange 2013 Server on CU11 and it failed. The GUI setup did not provide much info so looking at the ExchangeSetup.log i came across this error:
“Failed [Rule:LangPackBundleCheck] [Message:The language pack bundle could not be found or is corrupt.]
[REQUIRED] The language pack bundle could not be found or is corrupt.”
Open up Regedit and Navigate to the following:
Remove the Language Packs Key and re-run your setup, it should work fine now.
Hope it helps.