Hi Stewart, WebEditors and WebAdmins are Episerver default groups so you are not a member of those (as those don't exists in your computer local groups unless you create those). So the assumption is that developers are local Windows administrators - so if you can't log in, you most likely are not a Windows local administrator (member of the Administrators group)?

So if you are not a windows local admin you could modify the web.config and allow access for Users groups (as you definetly are a member of this windows group :D) OR some other windows group you are a member of.

So you need to replace the 'Administrators' string in web.config with 'Users' in three places:

under:
<virtualRoles addClaims="true">
<add name="CmsAdmins" type="EPiServer.Security.MappedRole, EPiServer.Framework" roles="WebAdmins, Users" mode="Any" />

under:
<location path="EPiServer">
<allow roles="WebEditors, WebAdmins, Users" />

under :
<location path="EPiServer/CMS/admin">
<allow roles="WebAdmins, Users" />

(above making the assumption in the location paths that you have not changed the 'uiUrl' from default)

Let us know if this helped you.