problem updating to 3.8

<sorry. duplicate>Hi. Just tried to update from Enfold 3.4 something to 3.8. I had made sure I had the latest WP upgrade before. Now getting 500 error, entire site and backend “Briefly unavailable for scheduled maintenance. Check back in a minute.” (that was hours ago). Other than going through FTP and completely re-uploading site. any ideas to rectify or at least avoid in future?

thanks. kate