Why does Apache Reverse Proxy Report OS 10048 in windows?

After a reverse proxy is set on the Apache server, the backend server cannot be connected for a period of time. After several seconds, the backend server can be automatically restored, after checking, it is found that the Apache error log contains the following words: [Error] (OS 10048) only one usage of each socket address (Protocol/network address/port) is normally permitted.: proxy: http: attempt to connect to localhost: 8080 (localhost) failed [Error] ap_proxy_connect_backend disabling worker for (host name) this problem occurs because the default TCP maxuserport is 5000 in windows, and port resources are quickly exhausted if reverse proxy is used. Generates an OS 10048 error. ap_proxy_connect_backend restarts all threads automatically. The solution is to create a maxuserport key in the registry to modify the default value of this parameter. The following is an explanation of this parameter on msdn:

Maxuserport

HKLM \ System \ CurrentControlSet \ Services \ Tcpip \ Parameters

Data Type	Range	Default Value
REG_DWORD	5,000-65,534 (Port Number)	5000

Description

Determines the highest port number TCP can assign when an application requests an available user port from the system. Typically,EphemeralPorts (those used briefly) are allocated to port numbers 1024 through 5000.

Note

Windows 2000 does not add this entry to the Registry. You can add it by editing the registry or by using a program that edits the registry.