Get this error
We're sorry, an internal error occurred that prevents the request to complete.
1. Go to yourstore.com/admin
and go to System -> Log and inspect the Errors.
2. If you can't access the administration you have to change your Web.config
file by replacing RemoteOnly with Off:<customErrors defaultRedirect="errorpage.htm" mode="RemoteOnly">
to <customErrors defaultRedirect="errorpage.htm" mode="Off">
Once you got the error it is much easier to know what is wrong.