ArcGIS Server Manager may be unable to correctly process the Windows user account password. This is a known bug with ArcGIS Server Manager and will be addressed in a future patch release. Please change the password for the Windows user account being used when logging in to ArcGIS Server Manager. See the Related Information section below for more info on how to do this.
After changing the password, please log out of Windows and then log back in to ensure the changes have taken effect.
To successfully log into Manager, the user must be a part of the ArcGIS Server Administration group (agsadmin) and the local Administrators group. Please take a look at the steps mentioned below to fix this problem.
Solution or Workaround
Right-click My Computer on the desktop and click 'Manage'. This opens a new window titled 'Computer Management'.
In the left pane, expand 'Local Users and Groups' node and click 'Group'. All the groups are listed in the right pane.
Verify that the user account for logging in to Manager is a member of both the Administrators and agsadmin groups. To do this, double-click the Administrator group and verify if the user is listed as a member. Repeat the same procedure for agsadmin group.
To add an account to these groups, it is necessary to restart IIS for the group membership to take effect.
Make sure to log off the machine and log back on to ensure the changes have taken effect.
To restart IIS, click Start > Run. In the command window, type 'iisreset'.