Would you mind telling us:

• which page you saw the error on?
• how you were attempting to remove the user?

I managed to reproduce a similar problem (except no error message was displayed) using the following steps:

1. Sign in as an Administrator
2. Create a new project role, Responsable.
3. Assign the Administer Projects permission to the Responsable role for some permission scheme.
4. Edit a user who doesn't have the Administer Projects permission and add the Responsable project role for a project that is using the permission scheme that you just modified.
5. Edit the user again and attempt to remove the Responsable project role you just granted.

The role will not be removed from the user and the error "You can not remove a user/group that will result in completely removing yourself from this role." will be returned by the ProjectRoleService - but no error will be displayed on the View Project Roles page.

Until we can get this fixed (the roots of the problem look quite complex) I can recommend the following workaround:

1. Temporarily remove the Administer Projects permission from the Responsable role.
2. Remove the user's membership from the Responsable role.
3. Re-add the Administer Projects permission to the Responsable role.

If you don't want to muck around with Responsable's permissions, you'll have to get an administrator who derives their administration priviliges from a different group/role to remove the user's membership.

Hope this helps!

cheers,
Tim

Note that for users without global admin rights, the error "You can not remove a user/group that will result in completely removing yourself from this role." will still be shown!

The EditUserProjectRoles action now also correctly displays any errors when editing role membership.