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Answer: Configuration in .NET is performed using one or more configuration providers. Given one or more configuration sources, the IConfiguration type provides a unified view of the configuration data. (S1)

Basics

• Configuration is read-only, and the configuration pattern isn't designed to be programmatically writable. (S1)
• .NET console apps created using the dotnet new command template or Visual Studio by default don't expose configuration capabilities. (S1)
• To add configuration in a new .NET console application, add a package reference to Microsoft.Extensions.Configuration. (S1)

Providers

• Several types of providers rely on various configuration sources. (S2)
• FileConfigurationProvider is the base class for loading configuration from the file system. (S2)
• The JsonConfigurationProvider class loads configuration from a JSON file. (S2)
• All of the file configuration providers throw the FormatException when duplicate keys are found in a single provider. (S2)

Claims

• id: C1 claim: Configuration uses providers. source: S1 evidence: "Configuration in .NET is performed using one or more configuration providers."
• id: C2 claim: Configuration is read-only. source: S1 evidence: "Configuration is read-only"
• id: C3 claim: JsonConfigurationProvider reads JSON. source: S2 evidence: "The JsonConfigurationProvider class loads configuration from a JSON file."
• id: C4 claim: Duplicate keys throw FormatException. source: S2 evidence: "When keys are found by multiple providers"

Sources

• [S1] Configuration - .NET. Microsoft Learn (.NET docs). https://learn.microsoft.com/en-us/dotnet/core/extensions/configuration . License: CC BY 4.0 (dotnet/docs). Accessed 2026-11-04.
• [S2] Configuration providers - .NET. Microsoft Learn (.NET docs). https://learn.microsoft.com/en-us/dotnet/core/extensions/configuration-providers . License: CC BY 4.0 (dotnet/docs). Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_tme105k5,
  author = {{iinventedlight}},
  title = {{Configuration and configuration providers in .NET}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/dotnet-configuration/},
  note = {Permanent ID iil:note:tme105k5. License: CC-BY-4.0.},
}

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