"The application lost connection with the motion controller"

[cncdrive]

Yes, max. RAM memory usage can definately cause lost connection issues, because then the UCCNC can no longer use memory and so it cannot communicate with the motion controller fast enough.
Memory problems like that so far we only see in regards video card driver problems.
The issue is that some video card drivers have űopenGL implentation bugs.
OpenGL is a graphics hardware acceleration standard and it is a very complex standard and some video cards implement some things incorrectly.
We saw some cases when the video card simply did not release graphcs resources like images properly filling up the video memory and then the RAM.
So far all these problems at customers got solved usually with updating or downgrading the video card drivers and in a few cases customers changed video card in the computer.
However this kind of problem is not too usual, I mean maybe like 1 out of several thousands of customers had this kind of problem and as far as I remember all got it solved.

[Battwell]

for really long cuts. go to setting, appearance.
turn off toolpath view.

i have run a 96 hour job

[wmgeorge]

Have you turned off Windows Updates and taken the computer completely off the Internet? Windows likes to check your computer from time to time to see if all the programs are updated. My shop computer is 100% offline and updates turned off.

[Parkgrr]

@Battwell Wow! You definitely have me beat. I think the highest I've gone is 40. I will definitely turn off toolpath view.

@wm, yes, totally disconnected from the internet. Is there a version/service pack that UCCNC is supposed to work with? It is very clearly not working with mine, I have about 4 different fatal errors occurring with varying frequency.

@ All, unfortunately it's become clear that this is not a memory issue. I recently left the machine just on, not running, with no program loaded for about 24 hrs and it disconnected with this error around the same time. I was there the moment it happened and I checked memory/CPU usage and all was normal. @CNCDrive how should I go about fixing this with memory, CPU, and voltages ruled out?

[Parkgrr]

Following up