A post about one of the most random problems ever. I was pulling my hair out for a while on this one, thus this definitely deserves the right to be highlighted in the “” category.Friday Case

As I have to install quite few versions of Sitecore locally (for every customer I work with actually), I came up with a sort of nomenclature for my local hostnames:


For example:


The decision to use “X” between version and revision was openly stolen from Andrew, a colleague of mine. This gives me and idea of which exact version I am using, plus provides with an ability to add all .local.com sites to Trusted Zone and fuggedaboutit.
The install happens via a PowerShell script

Now just about recently I noticed that after install I cannot log into Sitecore anymore with the default credentials. The strangest thing ever, it works in any browser other than IE. The login page posts back without giving me any indication:


The log files were not particularly helpful either:

6344 10:01:56 INFO AUDIT (sitecore\admin): Login
6860 10:01:57 INFO AUDIT (sitecore\Anonymous): Logout
6860 10:01:57 WARN Protected page accessed with no current user
4892 10:02:42 INFO AUDIT (sitecore\admin): Login
3240 10:02:42 INFO AUDIT (sitecore\Anonymous): Logout
3240 10:02:42 WARN Protected page accessed with no current user

Then I noticed the difference between other instances where everything worked just fine. The difference was the underscore character in the hostname which I started using just recently:http://clean_641x110720.local.com/

Did not take much time to find why

Avoid using the underscore () character in machine names. Internet standards dictate that domain names conform to the host name requirements described in Internet Official Protocol Standards RFC 952 and RFC 1123. Domain names must contain only letters (upper or lower case) and digits. Domain names can also contain dash characters ( - ) as long as the dashes are not on the ends of the name. Underscore characters ( _ ) are not supported in the host name._

Mamma Mia! I should be reading the standards more. Had no idea.

Hope this helps in case if you find yourself breaking your neck like myself.