How to turn on debug logging in the Windows Time Service

Applies to: Windows 10, version 2004, all editionsWindows Server, version 2004, all editionsWindows 10, version 1909, all editions


This step-by-step article describes how to turn on debug logging for the Windows Time service (also known as W32time). If you are an administrator, you can use the debug logging feature of the Windows Time service to help troubleshoot issues.

Note Microsoft recommends that you use debug logging after you have performed all other troubleshooting steps. Because of the nature of the detailed information in the debug log, you may have to contact a Microsoft Support Professional.

Turn On Debug Logging for the Windows Time Service

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows

To turn on debug logging in the Windows Time service:
  1. Start Registry Editor.
  2. Locate and then click the following registry key:
  3. On the Edit menu, click New Value, and then add the following registry values:
    • Value Name: FileLogSize
      Data Type: DWORD
      Value data: 10000000

      This registry value specifies the size of the log file in bytes.
      A value of 10000000 bytes will limit the log file to approximately 10 MB.
    • Value name: FileLogName
      Data Type: String
      Value data: C:\Windows\Temp\w32time.log

      This registry value specifies the location of the log file. The path is not fixed. You can use a different path.
    • Value name: FileLogEntries
      Data Type: String
      Value: 0-116

      This registry value specifies the level of detail of the information in the debug log. If you must have more detailed logging information, contact a Microsoft Support Professional.

      Note The Data Type value must be of type REG_SZ (String). You must type the value exactly as shown (that is, type 0-116). The highest possible value is 0-300 for most detailed logging. The meaning of this value is: Log all entries within the range of 0 and 116.