The switch models we use are ERS4950 (firmware: 7.6.1.033) and ERS 4850 (firmware: 5.7.0.008).
The version of Extreme Management Center: 8.1.3.65
The method that I am using: clicking right on the device select Configuration/Firmware - Backup configuration.
While busy it is saying, Management Center Archive - Executing SFTP Operation..
We need more detail information on the issue. Which switch model are you trying to configuration backup and firmware version of the switch and XMC? Abd which file transfter method (e.g. SCP, TFTP, etc.) are you using for the backup?