Store web site went down for no reason

I have a store that I started hosting on DiscountAsp.net over a week ago. It just went down and displayed the dreaded:

An error occurred while starting the application.
.NET Framework 4.7.2650.0 X86 v4.0.0.0    |   Microsoft.AspNetCore.Hosting version 2.0.0-rtm-26452    |    Microsoft Windows 6.3.9600    |   Need help?

In an attempt to debug the cause, I edited the web.config to set customErrors to Off. In doing that, the application restarted by itself and came up normally. I did not make any changes to the code or configuration prior to the site going down.

I contacted DiscountAsp.net tech support and they pointed me to a thread on this forum, which discusses various causes of the error. In my case, the site was running smoothly for over a week and then just sputtered.

https://www.nopcommerce.com/boards/t/49550/an-error-occurred-while-starting-the-application.aspx

I would appreciate any thoughts on why this might have happened or how to diagnose future occurrences (if any).

Here is the solution: https://www.nopcommerce.com/boards/t/49925/problem-running-40.aspx

My host has .NET Core 2.0.7 installed, but not 2.1. Does nopCommerce 4.0 require a specific version? They also suggested that I could change my app to "self-contained mode" if 2.1 was required.

So, nopCommerce requires the .NET Core 2.x.x runtime. Is the dependency for any particular version? My application went down and it was suggested that the cause was missing the Core library. My host has 2.0.7 installed. Does that fact invalidate the contention that this was the cause of the site going down?