System.ArgumentNullException: 'Value cannot be null. Paramet

Question

Hi Team I have this error System.ArgumentNullException:Value cannot be null, Parameter name:connectionString. private static string s_deviceConnectionString = Environment.GetEnvironmentVariable("IOTHUB_DEVICE-CONN_STRING"); launchSetting.json { "profiles": { "TwinDeviceApplication": { "commandName": "eNtsaIOTHubs", "environmentVariables": { "IOTHUB_DEVICE-CONN_STRING": "HostName=eNtsaIOTHubs.azure-devices.net;DeviceId=eNtsaDeviceId;SharedAccessKey=*** } } } } DeviceClient deviceClient = DeviceClient.CreateFromConnectionString(s_deviceClientConnectionString, s_ transportType); What am i missing? Isnt my deviceClient object has to launch this setting.json file to createConnectionString? Please assist me, thanks.

Priyanka Jain · Answer

You need to add connection string in appSetting.json file instead of launchSetting.json file Refer below link for more details https://stackoverflow.com/questions/51605177/net-core-how-can-i-set-the-connection-string https://dzone.com/articles/dynamic-connection-string-in-net-core

Priyanka Jain · Answer

I have referred many links in all these references I have not found connection string to be defined in launchSetting.json file https://blog.elmah.io/individual-developer-settings-in-asp-net-core/ https://dotnetcore.show/episode-10-configuration-in-net-core/

Hemant Jindal · Answer

Hi launchsettings.json is used to define environment like development, staging etc., for each environemnt you can define environment variables. you can refer this link for more details on how to use launchsetting.json in .net core application. this is applicable for any kind of application including azure https://www.talkingdotnet.com/launchsetting-json-in-aspnet-5/ https://docs.microsoft.com/en-us/aspnet/core/fundamentals/environments?view=aspnetcore-2.2

Guest User · Answer

Hi Is this rule applied to Microsoft Azure?