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AddFeatureManagement doesn't Register a Custom Configuration #546
Description
Nuget version affected: 4.2.0 (worked in 4.0.0 until nuget updated)
In my Program.cs:
builder.Services.AddFeatureManagement(builder.Configuration.GetSection("FeatureFlags"));
GetSection confirmed to retrieve the configuration from appsettings.json which is:
"FeatureFlags": { "UseReecoUsers": true }
but when calling IsEnabledAsync with the manager I received the following log:
"The feature definition for the feature 'UseReecoUsers' was not found"
When changing the feature flag section to:
"FeatureManagement": { "UseReecoUsers": true }
and changing the line in Program.cs to:
builder.Services.AddFeatureManagement(/*builder.Configuration.GetSection("FeatureFlags")*/);
it identifed the feature flag.
Activity
micheltol commentedon Jun 30, 2025
I can confirm this issue. It worked with version 4.1.0
zhiyuanliang-ms commentedon Jun 30, 2025
Hi, Michel Tol (@micheltol) daniell-reeco
I am sorry about this issue. This is an oversight. It is a bug introduced in 4.2.0.
In 4.2.0, we added an enhancement #536 that we will merge Microsoft feature flags from different configuration sources.
This enhancement will make the operation to GetMicrosoftFeatureDefinitionSections becomes more time-consuming.
Before 4.2.0, we will get all configuration sections for feature definitions and find the feature flags among them each time when there is no cache. code
In 4.2.0, to improve the performance, we will cache all configuration sections for feature definitions when constructing the
ConfigurationFeatureDefinitionProvider. code. So, until the configuration is changed, we only get all configuration sections for feature definitions for once and it happens in the constructor of theConfigurationFeatureDefinitionProvide.However,
the above the usage is something we called
RootConfigurationFallback. It will only be set totruewhen you provide anIConfigurationwhen callingAddFeatureManagement. TheRootConfigurationFallbackEnabledproperty ofConfigurationFeatureDefinitionProvideris set totrueafter the constructor of theConfigurationFeatureDefinitionProvider. code So, for the first time we call GetDotnetFeatureDefinitionSections in the constructor, theRootConfigurationFallbackEnabledwill not be respected. This caused the issue.I have sent out a bug fix PR: #547
Put more backgrounds here:
We have some back and forth on this feature. we even removed this feature in 3.0.0 and added it back in 3.1.0. #308 #312
You might have question: why we don't use
initkey word. Here is the reason.jimmyca15 commentedon Jun 30, 2025
Thanks for reporting this issue. Package version 4.2.0 has been unlisted
zhiyuanliang-ms commentedon Jul 10, 2025
daniell-reeco Michel Tol (@micheltol) 4.2.1 is released. It should fix the issue.