File lock error when using FileAppender with XmlConfigurator.ConfigureAndWatch (v3.3.1)

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#321 opened on Sep 18, 2026 1 comment 0 reactions 1 assignee View on GitHub

@FreeAndNil is already working on this.

Since Sep 19, 2026.

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Description

bug regression

When using the XmlConfigurator's file-watching, like this:

var logRepository = LogManager.GetRepository(typeof(Program).Assembly);
XmlConfigurator.ConfigureAndWatch(logRepository, new FileInfo("log.config"));

with a simple FileAppender config, like this:

<log4net>
	<appender name="log.log" type="log4net.Appender.FileAppender">
		<file value=".\log.log" />
		<layout type="log4net.Layout.PatternLayout">
			<conversionPattern value="%date %message%newline" />
		</layout>
	</appender>
	<root>
		<level value="ALL" />
		<appender-ref ref="log.log" />
	</root>
</log4net>

When editing the config-file at run-time, you get:
log4net:ERROR [FileAppender] ErrorCode: GenericFailure. Unable to acquire lock on file ...\log.log. The process cannot access the file '...\log.log' because it is being used by another process.

Due the file-change, the appenders are getting re-configured.
v3.3.0 old appenders were stopped and removed before new appenders were created and added.
v3.3.1 new appenders are created before old appenders are stopped.
The old appender still has a lock on the file.
The new appender is created and calls ActivateOptions()->OpenFile().

Dominant language: C#
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