Mainsail to Moonraker connection not starting

[oak flint]

Ender 3 Pro Pi4 BTT SKR E3 on Ethernet Connection
Clicked mainsail tag because GUI shows that is where the issue is on startup

I updated all configs in mid Feb with that big update, printed a few items, but today get error Mainsail to Moonraker not connecting.
1st problem I've had with this excellent Linux system.
Have printed happily for several years, no issues since switching from ' that other ' system !
Uploaded the recent updates , again a large package, today , same error.
Thank you for any thoughts, I read back on Github and here looking for comparables errors in the recent updates, but could not find anything I thought would fit.
Thank you for any help😀

[near bridge]

Ahoi @oak flint!
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[whole sinew]

Clicked mainsail tag because GUI shows that is where the issue is on startup

don't shoot the messenger. Mainsail just reports the error. Thats an klipper issue.
Just to be clear here: The message tells you klipper has no connection to the mcu (BTT SKR E3).
The moonraker connection is established.

so check your usb connection to your mcu and the serial path in your configuration.