Application is shutting down...

Hi,

My nopCommerce Version 4.0 site is crashing seemingly randomly (a couple of times a month)

I set stdoutLogEnabled="true" and when the site crashed I got the following log (this is just the last 30 lines of 702919 lines in the error log):

An exception was thrown attempting to execute the error handler.
System.InvalidOperationException: Operations that change non-concurrent collections must have exclusive access. A concurrent update was performed on this collection and corrupted its state. The collection's state is no longer correct.
   at Nop.Web.Framework.Infrastructure.Extensions.ApplicationBuilderExtensions.<>c.<UseNopExceptionHandler>b__1_1(HttpContext context) in C:\Users\Joe\Desktop\x\Presentation\Nop.Web.Framework\Infrastructure\Extensions\ApplicationBuilderExtensions.cs:line 83
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.Invoke(HttpContext context)
fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
      An unhandled exception has occurred while executing the request.
System.InvalidOperationException: Operations that change non-concurrent collections must have exclusive access. A concurrent update was performed on this collection and corrupted its state. The collection's state is no longer correct.
   at Nop.Web.Framework.Infrastructure.Extensions.ApplicationBuilderExtensions.<>c.<UseNopExceptionHandler>b__1_1(HttpContext context) in C:\Users\Joe\Desktop\x\Presentation\Nop.Web.Framework\Infrastructure\Extensions\ApplicationBuilderExtensions.cs:line 83
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[2]
      Request finished in 132.9148ms 500 text/html; charset=utf-8
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
      Request starting HTTP/1.1 GET http://www.hereshealth.ie/favicon.ico  
info: Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware[2]
      Sending file. Request path: '/favicon.ico'. Physical path: 'C:\data\sites\hereshealth.ie\wwwroot\favicon.ico'
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[2]
      Request finished in 1.4663ms 200 image/x-icon
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
      Request starting HTTP/1.1 POST http://127.0.0.1:33469/iisintegration  0
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[2]
      Request finished in 0.0876ms 202
Application is shutting down...


If I restart the Application Pool the site comes back.
Any ideas on how to fix this permanently?

Kind regards,
Joe