This may help or get you one step closer. The upgrades worked on live sites however the localhost developed problems. What worked for me was:
1. FTP to themename\plugins (if using wp 3.8.1) and rename the better-wp-security folder placing OLD at front of folder name.
2. I was then able to login using the wp-admin path
3. Once logged in to the site you’ll see that the iThemes security plugin is deactivated.
4. Rename the better-wp-security folder to original name – removing the OLD
5. Re-activate the plugin and it should work now. Should…at least it did for me.
Things I noticed before the problems. With 3.x version of better-wp-security there was the ability to rename the 3 login paths. With 4.x version this was reduced to 1 and it displayed a login path that I had set for the author but not the admin. I updated that path name and things started to go wrong from there.
I also had the custom-login plugin active so my login path, custom or wp-admin, only showed a blank webpage.
I had do rename the custom-login plugin to OLD and reactivate it after testing the previous 5 steps.
Hope this helps.