EventLog.WriteEntry Method (String, String, EventLogEntryType)
Writes an error, warning, information, success audit, or failure audit entry with the given message text to the event log, using the specified registered event source.
Assembly: System (in System.dll)
public static void WriteEntry( string source, string message, EventLogEntryType type )
The source value is an empty string ("").
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The source value is null.
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The message string is longer than 31,839 bytes (32,766 bytes on Windows operating systems before Windows Vista).
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The source name results in a registry key path longer than 254 characters.
The registry key for the event log could not be opened.
type is not a valid EventLogEntryType.
The operating system reported an error when writing the event entry to the event log. A Windows error code is not available.
Use this method to write an entry of a specified EventLogEntryType to the event log, using a source already registered as an event source for the appropriate log. The type is indicated by an icon and text in the Type column in the Event Viewer for a log.
The message string cannot contain %n, where n is an integer value (for example, %1), because the event viewer treats it as an insertion string. Because an Internet Protocol, version 6 (IPv6) address can contain this character sequence, you cannot log an event message that contains an IPv6 address.
You must create and configure the event source before writing the first entry with the source. Create the new event source during the installation of your application. This allows time for the operating system to refresh its list of registered event sources and their configuration. If the operating system has not refreshed its list of event sources, and you attempt to write an event with the new source, the write operation will fail. You can configure a new source using an EventLogInstaller, or using the CreateEventSource method. You must have administrative rights on the computer to create a new event source.
The source must be configured either for writing localized entries or for writing direct strings. The WriteEntry method writes the given string directly to the event log; it does not use a localizable message resource file. Use the WriteEvent method to write events using a localized message resource file.
If your application writes entries using both resource identifiers and string values, you must register two separate sources. For example, configure one source with resource files, and then use that source in the WriteEvent method to write entries using resource identifiers to the event log. Then create a different source without resource files, and use that source in the WriteEntry method to write strings directly to the event log using that source.
If the message parameter contains a NUL character, the message in the event log is terminated at the NUL character.
The following example writes a warning entry to an event log, "MyNewLog", on the local computer.