sandbox internal error - Maximum number of users was exceeded, this license allows 10 users for limitation type 'NAMED'

Hi,

Doing some tests in a sandbox app and after adding some test users (7 local, 2 mendix useraccounts part of the project team). We encounter an error and we do not get a login form anymore. Since we do not get a login form, I cannot access the application and (if this would be the cause) remove a user account.

How to continue? Can I delete a sandbox environment (or start over with a emptied database) without having to delete the full project (since I do want to continue testing and keep my version history)? Or is there any other way to resolve issue like this?

Thanks.

EDIT: Using a startup flow that deletes a number of user accounts enabled me to access the application again. Thanks all for your assistance.

The log entries:

9:40:08 AM APP INFO Apr 01, 2016 7:40:08 AM org.openid4java.consumer.ConsumerManager verifySignature
9:40:08 AM APP INFO Verification succeeded for: https://mxid2.mendixcloud.com/mxid2/id?id=491cfa50-11de-47e5-bd6b-d0ecdef42f64
9:40:09 AM APP WARNING OpenID: Failed to update user roles for 'https://mxid2.mendixcloud.com/mxid2/id?id=491cfa50-11de-47e5-bd6b-d0ecdef42f64', permissions for this user might be outdated
9:40:09 AM APP WARNING OpenID: com.mendix.core.CoreException: com.mendix.modules.microflowengine.MicroflowException: com.mendix.core.CoreRuntimeException: com.mendix.systemwideinterfaces.MendixRuntimeException: com.mendix.core.CoreException: com.mendix.core.CoreRuntimeException: com.mendix.systemwideinterfaces.MendixRuntimeException: com.mendix.core.util.license.LicenseRuntimeException: Maximum number of users was exceeded, this license allows 10 users for limitation type 'NAMED'
9:40:09 AM APP INFO at AppCloudServices.InvokeOnNonFirstLoginAppCloudUser (Change : 'Change 'User'')
9:40:09 AM APP INFO Advanced stacktrace:
9:40:09 AM APP INFO at com.mendix.core.component.InternalCore.execute(InternalCore.java:352)
9:40:09 AM APP INFO Caused by: com.mendix.modules.microflowengine.MicroflowException: com.mendix.core.CoreRuntimeException: com.mendix.systemwideinterfaces.MendixRuntimeException: com.mendix.core.CoreException: com.mendix.core.CoreRuntimeException: com.mendix.systemwideinterfaces.MendixRuntimeException: com.mendix.core.util.license.LicenseRuntimeException: Maximum number of users was exceeded, this license allows 10 users for limitation type 'NAMED'