TechNote

Flash Media Server error "Asynchronous I/O operation failed (Failed to attach to completion port: The parameter is incorrect. 87)"

Issue

In rare cases, RTMP NetConnections to Flash Media Server may fail with the following log entry in the core.log of Flash Media Server:

Asynchronous I/O operation failed (Failed to attach to completion port: The parameter is incorrect. 87).

Note: It is possible that RTMPT and RTMPS connections work fine, even on identical ports.

Reason

This error occurs when a NetConnection was received on the internal edge process but the connection to the completion port could not be established.

There are several reasons why this can happen. Typically, third-party socket wrappers with incomplete implementations are the cause,includinganti-virus programs, personal firewalls, and connection manipulation tools such as NetLimiter.

Another common cause is the Microsoft Windows XP system restore feature. While Microsoft Windows XP is not a supported operating system for Flash Media Server, it is supported for developer machines. The system restore process may change bindings in the winsock network stack. When this happens, Flash Media Server is not able to create the connection to the completion port and the above error occurs.

Solution

As there are different causes for the issue, there are different solutions. Below is the list of actions that Adobe recommends:

Check your system for software that may wrap sockets, such as personal firewalls, anti-virus software, or bandwidth-shaping tools. Shut down Flash Media Server, disable these tools, and eventually uninstall them from your server.
Check the winsock settings and try to fix them. The following Microsoft article explains how to do this: http://support.microsoft.com/kb/811259. If WinXP SP2 is present, then type netsh winsock reset on the command line and reboot the system. Alternative winsock repair tools are available. It is important to point out that any such changes should be done with extreme care, and it is advisable to read the Microsoft article regardless of what method is used to repair winsock.
Repair the relevant networking components by repairing Microsoft Windows, reinstalling the driver kit and/or all third-party NIC drivers.