Configure:
<appender name="TelegramAppender" type="log4net.Appender.Telegram.TelegramAppender, log4net.Appender.Telegram">
<ChatId>Your User ID</ChatId>
<Token>Your Telegram Bot Token</Token>
<filter type="log4net.Filter.LevelRangeFilter">
<param name="LevelMin" value="ERROR" />
<param name="LevelMax" value="FATAL" />
</filter>
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%message" />
</layout>
</appender>Use:
LogManager.GetLogger(string.Empty).Fatal("Fatal message");Appender is non-blocking. What is why call LogManager.Shutdown(); when application finishes.