How do I prevent this IIS error that required a manual restart of the app pool from occurring again?

My website hosted in IIS became inaccessible. In the event log on the server, I saw this error:

Event code: 3005 
Event message: An unhandled exception has occurred. 
Event time: 01/01/2018 00:00:00 AM 
Event time (UTC): 01/02/2018 6:00:00 AM 
Event ID: 64b4d6533abd4e71b3ba30b9008d7d86 
Event sequence: 1921230 
Event occurrence: 1 
Event detail code: 0 

Application information: 
    Application domain: /LM/W3SVC/2/ROOT-1-131865989552967444 
    Trust level: Full 
    Application Virtual Path: / 
    Application Path: C:\inetpub\wwwroot\MyWebsite\ 
    Machine name: MyWebServer

Process information: 
    Process ID: 3388 
    Process name: w3wp.exe 
    Account name: NT AUTHORITY\SYSTEM 

Exception information: 
    Exception type: HttpException 
    Exception message: The remote host closed the connection. The error code is 0x80070057.
   at System.Web.Hosting.IIS7WorkerRequest.RaiseCommunicationError(Int32 result, Boolean throwOnDisconnect)
   at System.Web.Hosting.IIS7WorkerRequest.ExplicitFlush()
   at System.Web.WebSocketPipeline.DoFlush()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Web.WebSocketPipeline.<ProcessRequestImplAsync>d__9.MoveNext()



Request information: 
    Request URL:  
    Request path:  
    User host address:  
    User:  
    Is authenticated: False 
    Authentication Type:  
    Thread account name: NT AUTHORITY\SYSTEM 

Thread information: 
    Thread ID: 112 
    Thread account name: NT AUTHORITY\SYSTEM 
    Is impersonating: False 
    Stack trace:    at System.Web.Hosting.IIS7WorkerRequest.RaiseCommunicationError(Int32 result, Boolean throwOnDisconnect)
   at System.Web.Hosting.IIS7WorkerRequest.ExplicitFlush()
   at System.Web.WebSocketPipeline.DoFlush()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Web.WebSocketPipeline.<ProcessRequestImplAsync>d__9.MoveNext()


Custom event details: 

Restarting only the website caused the error to be logged again, but with a different code (0x800704CD instead of 0x80070057). The website was still inaccessible. Restarting the app pool resolved the issue.

What is this error, and how can I stop it from happening again?

Googling both error codes yields results from people who were encountering the error intermittently (post1, post2). The difference is that their websites don't appear to be brought down by this error, and they are seeing the error intermittently. I saw it twice, and had to manually intervene just to get the website running again.