Mathematica has been closing the kernel mid-way through evaluating a notebook, exactly as if I had done Evaluate > Quit Kernel. This happens seemingly at random every 3 hours or so and if I re-evaluate the notebook it usually runs fine. It has been happening ever since version 11.2 and now I am trying 12.1, but this still has the same problem. It has affected installations on several different Windows PCs and on many different notebooks, but never happened in 11.1 and prior. It has been the subject of numerous technical support inquiries, but its random nature means it is not repeatable. Has anyone else had this problem and found a solution?

Thanks for your comments, but I fear you are barking up the wrong tree. This has happened on dozens of notebooks, on 4 different PCs and on 4 different versions of Mathematica (11.2-12.1). Yet it has never happened in exactly the same place twice and every time I recalculated or closed and reloaded, it either worked fine or failed somewhere else in the notebook. It has never happened on 11.1, which is the only version that I can use, so I use it all the time. None of that would be the case for a syntax error or two. The simplest example I have ever seen it happen on was a single cell x=5; x which replied x once and 5 every other time. I agree that tracing errors can be difficult, but even I could manage with that example. I don't know if I have a pre-release version of 12.1 - it was what Wolfram sent me to evaluate, but it has been the same for 11.2,11.3 and 12.0. This has been going on for years (when did 11.2 come out? 2017?) and I was hoping that there was someone who had experienced the same, who had got further in finding a solution.

Has anyone else had this problem and found a solution? This is not a general problem, but a crash bug triggered by something specific you do. Wolfram will only be able to fix this if you can identify the specific command, or sequence of commands, that causes the crash. Sometimes crashes are not fully deterministic, but there is still one specific evaluation that causes them (just not 100% of the time). In short, the only thing that can be done is to track down the offending evaluation (which, admittedly, is often a lot of work). Once you do, report it, and hopefully Wolfram will fix it. You can also ask here (or on https://mathematica.stackexchange.com/) for an alternative way to perform the same operation without a crash.

It may well be a hardware/OS issue, but it has happened on 4 different PCs. All had very different hardware in terms of processors, motherboards, graphics cards etc., but all were running Windows 10 Pro and all were on the same network. The PC I am currently trying it on has not hosted Mathematica before, but is exhibiting the same symptoms as the others. I have not noticed any commonality in the calculation types that fail and even if x=5; is an anomaly (it is certainly not typical), failures often happen early in an evaluating notebook and those that use little RAM or other resources. The most recent technical support case number was 4266662.

Mathematica closing kernels