[[email protected] app]$ sencha upgrade
Sencha Cmd v7.2.0.56
[INF] Determining the latest version of Sencha Cmd
[INF] Downloading : ....................
[INF] The latest version of Sencha Cmd is 7.2.0.66
[INF] Downloading SenchaCmd-7.2.0.66-linux-amd64.sh.zip from http://cdn.sencha.com/cmd/7.2.0.66/no-jre/ to temp folder /tmp/sencha1588077104046
[INF] Cleaning up temporary files in /tmp/sencha1588077104046
[ERR] Error downloading http://cdn.sencha.com/cmd/7.2.0.66/n...x-amd64.sh.zip

Looks like someone bumped the version without providing the linux binary - I was able to download the windows version though.