I have the same issue – no site after “upgrade”
Plugins have been reset to a:0:{} and reviewing the link above gives me nothing I can use to resolve this. the autoupdater said that it had completed successfully, yet when I try to log in I get this.
Error message I receive
Server error!
The server encountered an internal error and was unable to complete your request.
Error message:
Premature end of script headers: index.php
If you think this is a server error, please contact the webmaster.
Error 500
Any thoughts would be appreciated.