MythTV Official Community Forum

Make sure the <chanid> is valid. The mysql command on the Wiki will give you
a list if you don't know yours. Or, you can plug this into your browser. It will even
give you the IconURLs:

<backend>:6544/Channel/GetChannelInfoList

Also, if you want to take an icon that works, go to:
https://www.lyngsat-logo.com/tv/w_1.html

and right click on any one and save it in place of a failing one.

For macports installer, correct path for channels dir is /opt/local/var/mythtvuser/.mythtv/channels