Indeed, this seems fixed in later version. I just updated one of our nodes to version  6.10.80.00, the issue described in my first post has gone. When I was testing iDRAC version 6.10.30.00, the issue was sill there.
Hello, We were asked by DELL supporter to update iDRAC again for a hardware support, from 6.02.00.00 to 6.10.00.00. After updating, the secure web access to iDRAC failed with error: Bad Request Your browser sent a request that this server could not understand. Additionally, a 400 Bad Request error was encountered while trying to use an ErrorDocument to handle the request. After doing some tests, I have the following conclusions/workarounds: 1. the secure web access failed when using the FQDN of iDRAC interface 2. using the IP or short hostname works with the secure web access 3. setting iDRAC.WebServer.ManualDNSEntry to have the FQDN included won't solve the issue 4. disabling idrac.webserver.HostHeaderCheck aslo works, but could not open virtual console viewer   I tried to use racadm command 'sslresetcfg' to regenerate the certificate, but only short hostname used as Common Name (CN) and also only the short hostname listed in the DNS alternative name. By the way, we have DNS BMC/RAC Name and DNS Domain name correctly configured. It looks like to me a new bug in version 6.10.00.00. Though there are not issues with the IP and short hostname access, it is still annoying since we have FQDN defined and linked everywhere.   Thanks, Di
iDRAC 9 version 6.10.00.00 400 Bad Request error