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Release notes for Optimizely CMS and Customized Commerce updates


Release notes moved to a new location. As of May 15th, 2024, the release notes on the World site no longer receive updates. See Release notes by product on the Optimizely Support site.

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This topic lists Optimizely updates, delivered as NuGet packages and services. You decide which updates apply to your project.

Select a product, package, or service in the left menu, and then select one of the following filters from Item type and click Filter.

  • Bug – Display bug fixes.
  • Critical bug – Display only critical bug fixes.
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  • Security - Display only security updates.

Note: NuGet packages listed here may not be immediately available in the Optimizely NuGet feed.

Latest changes

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Area ID Type Description Released
  Log4Net logging stops working in Release mode

All log4net logging stops working when running in release mode. Only affects EPiServer.Logging.Log4Net v2.2.1

Add the following AppSettings to the web.config.

    <add key="log4net.Config" value="EPiServerLog.config"/>
    <add key="log4net.Config.Watch" value="True"/>

Reported through

EPiServer.Logging.Log4Net 2.2.2; (Or a related package);
Feb 19, 2018
  Initialization module using log4net directly disables logging
  1. Add the following intialization module:

        public class AA : IInitializableModule
            private static readonly log4net.ILog _log = log4net.LogManager.GetLogger("test");
            public void Initialize(InitializationEngine context)
            public void Uninitialize(InitializationEngine context)

EXPECTED: Logging works
ACTUAL: Logging stops working

Note: Sometimes for this bug fix to take affect you have to clear "Temporary ASP.NET Files", ie C:\Windows\Microsoft.Net\Framework64\v4.0.30319\Temporary ASP.NET Files\

WORKAROUND: An easy fix is to use namespace EPiServer.Logging.Compatiblity instead of log4net, to make sure log4net can be safely initialized from CMS instead from a custom initialization module.

EPiServer.Logging.Log4Net 2.2.1; (Or a related package);
Feb 01, 2018