Semaphore Timeout Expired Issue When Communicating with Web Server

  • I've been encountering a persistent issue while attempting to read/write to a web server.

    The error message I'm receiving is

    A transport-level error has occurred (provider: TCP Provider, error: 0 - The semaphore timeout period has expired.)

    I've already ensured that the firewall is enabled and properly configured, and there don't seem to be any apparent network issues. Despite these precautions, the error persists. I'm seeking assistance in understanding the potential reasons behind this issue and any suggestions for resolving it.

    Note: This error is randomly occuring when communicating with web Server.

  • From my understanding, that problem comes up when there is an issue in the network stack. It is not usually firewall related. MS support says:

    Error 121: "The semaphore timeout period has expired" is a network related error, not a SQL Server timeout. The source of the issue can be related to your VPN if you are using a VPN or to Network connectivity problems

    https://learn.microsoft.com/en-us/answers/questions/545360/the-semaphore-timeout-period-has-expired

    Google tells me that the problem is usually caused by something bad in the network stack such as failing network hardware, bad drivers, bad cables, etc.

    It is probably something with the network between the 2 machines. Doing an extended ping session (if ICMP echo is allowed) to look for dropped packets may help confirm if it is due to network issues. Won't help debug the problem, but you can then talk to the network team and get them to investigate further.

    The above is all just my opinion on what you should do. 
    As with all advice you find on a random internet forum - you shouldn't blindly follow it.  Always test on a test server to see if there is negative side effects before making changes to live!
    I recommend you NEVER run "random code" you found online on any system you care about UNLESS you understand and can verify the code OR you don't care if the code trashes your system.

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