Error fix for "Operation could not be completed (error 0x00000704). The specified port is unknown" when installing Brother printer software. It also fixed problem with not working Brother Monitor Status. Read more on my blog:

0x00000704_fix.reg

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors]

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors\Local Port]
"Driver"="localspl.dll"

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors\Standard TCP/IP Port]
"Driver"="tcpmon.dll"

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors\Standard TCP/IP Port\Ports]
"LprAckTimeout"=dword:000000b4
"StatusUpdateEnabled"=dword:00000001
"StatusUpdateInterval"=dword:0000000a
"TcpAckTimeout"=dword:0000012c

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors\USB Monitor]
"Driver"="usbmon.dll"

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors\USB Monitor\IppUsbAltIndex]

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors\WSD Port]
"Driver"="APMon.dll"

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors\WSD Port\Adapters]

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors\WSD Port\Adapters\IPP]

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors\WSD Port\Adapters\WSPrint]

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors\WSD Port\Adapters\WSPrint\OfflinePorts]

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors\WSD Port\Ports]

Worked, thanks for sharing!