[CLOSED] Intermittent Http Error 500 in Windows NLB load balaced environment

  1. #1

    [CLOSED] Intermittent Http Error 500 in Windows NLB load balaced environment

    Hi,

    We have an intermittent http error 500 that shown in modal dialog box and it is very hard for us to regenerate the issue.
    Sometimes it comes and sometimes it is not. The page can be accessed and all are working fine when We tested it.
    Our user mentioned that when they leave the page for a while then once they comes back and click any button to update or load data, that error will appeared.
    The error can be Http error 500 or sometimes also appeared "Communication Error".

    We deployed our Web application to 2 web application servers, load balanced using windows NLB.
    any issue with EXT.net to be deployed in Load balanced environment?

    May I have your advice?
    is there any way for me to check in Code, Web.Config, DNS, or IIS?


    Thanks
    Last edited by fabricio.murta; Sep 22, 2017 at 10:10 PM. Reason: no feedback from the user in 7+ days
  2. #2
    Hello @bapas1!

    I'm afraid this error should not be related to Ext.NET. You should be looking at your IIS server logs for the 500 errors. If the user received back a 500 error, then there should be logs in IIS about the failed request, and details about it.

    But when the user receives a communication failure, it means the browser sent a request to the server and it, in turn, didn't return the answer in the acceptable timeout. This can happen if either the server does not receive any request at all (network temporary failure or packet loss), the server sent back the response that never arrived for similar reasons, the operation may take an arbitrary amount of time or the server is overloaded during the request and couldn't process in a timely fashion -- the latter seems to be not very probable.

    Another thing that could be happening is your load balancing approach is breaking communication protocols' flows, like the XMLHTTPRequest is sent to a server an replied by another, or the HTTP session is kept in one server but absent in the other, and so on. In other words, the load balancing could be breaking protocols inherent of Ext.NET operation thus causing the failures. The protocols broken are not proprietary nor maintained by Ext.NET, but ASP.NET (as sessions or XMLHttpRequest).

    Well, I hope this helps delineate your research towards the solution of the problem. I suggest you try to take out the load balancing and have the same client perform the test to ensure the problem is not coming from any networks' unstability (this means trying individually with both nodes of the load-balanced environment). Then if not, looking at the logs for the 500 errors would be imperative. But again, no matter how I look at the error, this does not seem to be Ext.NET related and we can't really help much with that.
    Fabrício Murta
    Developer & Support Expert
  3. #3
    Hello @bapas1!

    It's been a while and still no feedback from you. Could you further in this issue with random IIS errors? Although it did not look like it was related to Ext.NET, maybe you could have found some more information that clarifies it as an Ext.NET issue that we could provide a better help with.

    Anyway, we'll leave this thread open for at least more 7 days. After that, given no feedback from you, we may be marking this thread as closed at any time. But since we don't lock up the thread, you will be able still to post a feedback here afterwards, so take your time.
    Fabrício Murta
    Developer & Support Expert

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