Azure function key vault data not accessible from .net core

I have an Azure function app .Net core solution from where, I am trying to access Azure key vault data, when the app is deployed. When in my local (development mode), I am accessing the key vault data from a local file (which is not deployed). Also, I want to have two more config files which will be deployed along with the app and will be used as per the environment where it is deployed. I am stuck at one point..I am using three json files * local.settings.json (for local) * prod.settings.json (for prod) * dev.settings.json (for non prod) This is how I am configuring in my startup: `if(env=prod) { var configBuilder = new ConfigurationBuilder() .SetBasePath(applicationRootPath) .AddJsonFile("prod.settings.json", optional: true, reloadOnChange: true) .AddEnvironmentVariables() .Build(); } else { var configBuilder = new ConfigurationBuilder() .SetBasePath(applicationRootPath) .AddJsonFile("dev.settings.json", optional: true, reloadOnChange: true) .AddEnvironmentVariables() .Build(); }` This is how I am accessing the data in startup: var fromKeyVault=Environment.GetEnvironmentVariable("keyVaultKey"); var fromJson=configBuilder.GetValue("devKey"); both fromKeyVault and fromJson works perfectly in my local but when I try to deploy and test in non prod, fromKeyVault always returns null. Do you see anything I can do to get a wayout of this issue. The connection configuration has no issue between the .Net solution and Azure key vault. Regards, Debottam I tried a few things like: configBuilder.GetValue("keyVaultKey"); even this works well in my local but gives null in non prod. The expectation is: * The key vault values will be taken up from local.settings.json in my local env and when in prod/non prod, it should be coming from Azure key vault. * In local, if any key is not present in local.settings.json then it should get it from dev.settings.json this behavior is also expected in environments.