Your 7942 appears to have been running 8.2.x.x.x according to the image control file name.
The fwupdate server is not active for standalone AP updates any longer. Current code does
have a Local method for upgrades.
For you to upgrade, you will need to setup an FTP server, choose the TFTP Method of upgrade,
put the server IP address in the Firmware Server field, and change the image control file name to
"zf7942_940_cntrl.rcks", after you download these two files and put them into your TFTP server's
The image control file is a text file with the firmware filename and byte count. Let us know
if you're able to upgrade with this information? With best regards.