Can't access AdminCP in vBulletin 5.1.0 Alpha 7

[Kent55]

When I try to access the adminCP I am given this error:

That action could not be completed. Please try again, and if this occurs again please contact the system administrator and tell them how you got this message.

I have the following files on my server:

.htaccess
web.config
htaccess.txt

Any Ideas?

Thanks in advance.

[Mark.B]

With the caveat that this is pre-release software and thus not supported.....

Is this a clean install, or an upgrade from a previous version? If so, which version?

[Kent55]

I understand that it isn't supported however I would still like to test it out, and with no access to the admincp makes that near impossible.
This is a fresh install.

[Lynne]

Is your forum located within a directory? And if so, did you edit the .htaccess file RewriteBase line?

RewriteBase /directory/