Windows Print Monitors and Spool Paths Registry Keys

This guide details the exact locations within the Windows Registry (regedit) where print monitor dynamic-link libraries (DLLs) are registered and where system-wide print spooler storage paths are configured.

Registered Print Monitor DLLs Registry Location

Windows catalogs all installed print monitor dynamic-link libraries under the Control\Print\Monitors key.

• Registry Path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors

How It Is Structured

Inside the Monitors key, each registered port monitor has its own dedicated subkey (for example, Local Port, Standard TCP/IP Port, USB Monitor, or third-party vendor monitors).

Within each monitor’s subkey, you will find the configuration values: * Driver (REG_SZ): Specifies the filename of the monitor’s dynamic-link library (e.g., localspl.dll, tcpmon.dll, or usbmon.dll). These files are typically stored in the C:\Windows\System32\ directory.

Print Spool Directory Paths Registry Location

The Windows Print Spooler uses registry entries to determine the global directory where temporary spool files (.SHD and .SPL) are written prior to printing.

• Registry Path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Printers

Associated Values

• DefaultSpoolDirectory (REG_SZ): Contains the file path for the spool folder. By default, this value is set to: C:\Windows\System32\spool\PRINTERS

Per-Printer Spool Path Overrides

Individual printers can also override the default spool path. When configured, these specific paths are stored under: * Registry Path: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Printers\[Printer_Name] * Value: SpoolDir (REG_SZ)