Symptoms

For the Web Verification Issues the first recommendation is to collect the corresponding logs as described here: https://help.abbyy.com/en-us/flexicapture/12/TroubleshootingGuide/tg_logs_webstation 

In the logs the below error message may be found:

System. Net.Sockets SocketException: Only one usage of each socket address (protocol network address port) is normally permitted

Cause

TCP/IP stack is overloaded. Windows has a limitation on the number of sockets that can be opened in rapid sequence due to how sockets get closed under normal operation. Whenever a socket is closed, it enters the TIME_WAIT state for a certain time. Each time it is polled, a socket is consumed out of the default dynamic range, and each time that poll ends, that particular socket goes into TIME_WAIT. If it is polled frequently enough, eventually all of the available ports are consumed. 

Resolution

• Changing the Dynamic Port Range

1. Open regedit.
2. Open key HKLM\System\CurrentControlSet\Services\Tcpip\Parameters
3. Edit (or create as DWORD) the MaxUserPort value.
4. Set it to a higher number. (i.e. 65534)

• Changing the TIME_WAIT delay

1. Open regedit.
2. Open key HKLM\System\CurrentControlSet\Services\Tcpip\Parameters
3. Edit (or create as DWORD) the TcpTimedWaitDelay.
4. Set it to a lower number. Value is in seconds. (i.e. 60 for 1-minute delay)