Unable to use TCP ports above 49728 RRS feed

  • Question

  • Hi guys,

    I originally saw this issue within a Node.js app, but I've replicated it in a basic winsock TCP server example as well. Ever since the latest Windows Update, I'm unable to use ports above 49728 in my applications. I get access denied errors when I try to bond. 

    I've tried during all windows defender and firewall functionality off, but that seems to make no difference. I took a look through the release notes of the past few released, but couldn't find anything that seemed related to this.

    Has anyone experienced this? This has happened with two of my Windows machines (running Win10 Pro) after they restarted and received the latest update. 


    Wednesday, May 22, 2019 12:25 PM


All replies

  • Hello,

    the ports beginning with 49152 are dynamic ports: https://tools.ietf.org/html/rfc6335#section-8.1.2

    Applications can use them already or the OS can block them. It seems that the OS blocks the most of the numbers, maybe for its own use. If you want to know if Windows blocks them, you should ask in another forum, e.g.



    Regards, Guido

    Wednesday, May 22, 2019 12:41 PM
  • Thanks Guido,

    I felt like I was making a thread in the wrong place, but I couldn't figure out the correct forum, so thanks for linking me. I'm not super familiar with the microsoft forums. 


    Wednesday, May 22, 2019 1:03 PM
  • Hello,

    Thanks for posting here.

    >>Unable to use TCP ports above 49728.

    This forum is discussing and asking questions about the C++ development, I'm afraid your question is not related to this, so I will move this thread to Where is the Forum for...? forum to redirect it. So you could post your issue on the suitable forum.

    Thanks for your understanding and Cooperation.

    Best Regards,

    Jack Zhang

    MSDN Community Support Please remember to click "Mark as Answer" the responses that resolved your issue, and to click "Unmark as Answer" if not. This can be beneficial to other community members reading this thread. If you have any compliments or complaints to MSDN Support, feel free to contact MSDNFSF@microsoft.com.

    Thursday, May 23, 2019 8:28 AM
  • Another possible forum is:


    Richard Mueller - MVP Enterprise Mobility (Identity and Access)

    Thursday, May 23, 2019 12:36 PM