EnableTrace function (evntrace.h)

A trace session controller calls EnableTrace to configure how an ETW event provider logs events to a trace session.

This function is obsolete. The EnableTraceEx2 function supersedes this function.


  [in] ULONG           Enable,
  [in] ULONG           EnableFlag,
  [in] ULONG           EnableLevel,
  [in] LPCGUID         ControlGuid,


[in] Enable

Set to 1 to enable receiving events from the provider or to adjust the settings used when receiving events from the provider (e.g. to change level and keywords). Set to 0 to disable receiving events from the provider.

[in] EnableFlag

32-bit bitmask of keywords that determine the categories of events that you want the provider to write. The provider typically writes an event if the event's keyword bits match any of the bits set in this value or if the event has no keyword bits set, in addition to meeting the EnableLevel critera.


EventRegister-based providers support 64-bit keywords. Use EnableTraceEx2 to enable providers using a 64-bit MatchAnyKeyword mask.

[in] EnableLevel

A value that indicates the maximum level of events that you want the provider to write. The provider typically writes an event if the event's level is less than or equal to this value, in addition to meeting the EnableFlag criteria.

This value should be in the range 1 to 255. Microsoft defines the semantics of levels 1-5 as shown below. Lower values indicate more-severe events. Each value of EnableLevel enables the specified level and all more-severe levels. For example, if you specify TRACE_LEVEL_WARNING, your consumer will receive warning, error, and critical events.

Value Meaning
TRACE_LEVEL_CRITICAL (1) Abnormal exit or termination events
TRACE_LEVEL_ERROR (2) Severe error events
TRACE_LEVEL_WARNING (3) Warning events such as allocation failures
TRACE_LEVEL_INFORMATION (4) Non-error informational events
TRACE_LEVEL_VERBOSE (5) Detailed diagnostic events

The TRACE_LEVEL constants are defined in evntrace.h. Equivalent WINMETA_LEVEL constants are defined in winmeta.h.

[in] ControlGuid

The control GUID (provider ID) of the event provider that you want to enable or disable.


Return value

If the function is successful, the return value is ERROR_SUCCESS.

If the function fails, the return value is one of the system error codes. The following are some common errors and their causes.


    One of the following is true:

    • ControlGuid is NULL.
    • TraceHandle is NULL.

    You cannot change the enable flags and level when the provider is not registered.


    The provider is not registered. Occurs when KB307331 or Windows 2000 Service Pack 4 is installed and the provider is not registered. To avoid this error, the provider must first be registered.


    Exceeded the number of trace sessions that can enable the provider.


    Only users with administrative privileges, users in the Performance Log Users group, and services running as LocalSystem, LocalService, or NetworkService can enable event providers to a cross-process session. To grant a restricted user the ability to enable an event provider, add them to the Performance Log Users group or see EventAccessControl.

    Windows XP and Windows 2000: Anyone can enable an event provider.


Event trace controllers call this function to configure the event providers that write events to the session. For example, a controller might call this function to begin collecting events from a provider, to adjust the level or keywords of the events being collected from a provider, or to stop collecting events from a provider.

This function is obsolete. For additional functionality, new code should use EnableTraceEx2.

The following two function calls are equivalent:

// Obsolete:
Status = EnableTrace(

// Updated equivalent code:
Status = EnableTraceEx2(
    Enable,      // ControlCode
    EnableFlag,  // MatchAnyKeyword
    0,           // MatchAllKeyword
    0,           // Timeout
    NULL);       // EnableParameters

For additional details on the semantics of configuring providers for a session, refer to the documentation for EnableTraceEx2.


Requirement Value
Minimum supported client Windows 2000 Professional [desktop apps | UWP apps]
Minimum supported server Windows 2000 Server [desktop apps | UWP apps]
Target Platform Windows
Header evntrace.h
Library Advapi32.lib
DLL Advapi32.dll

See also