@issa1998 If you need help with workarounds please let me know.

@Wayne-Workman i’m trying to register dell optiplex 3020/7010 and hp desktop 600 g1/g2 sff , i’m using Ubuntu 12.04 tls

@issa1998 Sounds like you did not do a clean new install of the server operating system. So possibly the mysql database has still the information from your old installation. Can you please check on the web interface if you have any hosts there already?? Possibly the host you are trying to register already exists!?!