I have seen a similar error several times, and the problem has been that the email address is duplicate (so the error message seems very generic). But your stack trace implies that it fails to read the minimum required password length. Check the minRequiredPasswordLength attribute on your membership provider if it has a valid value etc.

Hi Magnus, 

I tried adding the minRequiredPasswordLength attribute but with no success. I've also tried using different passwords and still same error.

Any ideas are appreciated :)

Kjetil,

Just out of curiousity, what membershipprovider are you using?  

Either way, try using Community tab -> System Settings -> Groups/Users -> Add User instead.

That did the trick, Joel! thanks :)

I'm completly green when it comes to Relate+ and thought there were only one way of adding users (the old episerver way). Is the old way through admin mode supposted to work when using the out of the box demo template site?

As far as I know the EPiServer.Common.Web.Authorization.MembershipProvider (the default provider which wraps around EPiServer Communitys own security system) supports creating new users but it doesn't support retrieval of information such as minimum password length. As it seems that the EPiServer CMS admin mode validates minimum password length adding new users that way won't work with that provider :(

But there is still hope... :)

As of the current hotfix version of EPiServer Common (where the mentioned MembershipProvider resides), the previously unimplemented properties are now implemented.

http://world.episerver.com/en/Download/Items/Hotfixes/EPiServer-Common/Hotfix-1---EPiServer-Common-23/

I had the exact same error but the wrong e-mail was not the reason.

Be sure to check the logfiles written out by EPISERVER, there you have a good chance of figuring out what the reason for the error is.  In my case, the transaction log of the database was full...  I shrank the log and voila, everything worked fine again! :-)