Console.WriteLine sometimes throws the handle is invalid exception-CodePudding

I have an Azure function which has this line of code:

Console.WriteLine("Name: "   list.Count());

This line sometimes throws this exception:

The handle is invalid.

at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
at Microsoft.Azure.WebJobs.Host.Executors.FunctionExecutor d__26.MoveNext (Microsoft.Azure.WebJobs.Host, Version=3.0.34.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35: C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Executors\FunctionExecutor.cs:352)
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e) at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e) at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult (System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e) at Microsoft.Azure.WebJobs.Host.Executors.FunctionExecutor d__18.MoveNext (Microsoft.Azure.WebJobs.Host, Version=3.0.34.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35: C:\projects\azure-webjobs-sdk-rqm4t\src\Microsoft.Azure.WebJobs.Host\Executors\FunctionExecutor.cs:108) Inner exception System.IO.IOException handled at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw: at System.ConsolePal WindowsConsoleStream.Write (System.Console, Version=4.1.2.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a) at System.IO.StreamWriter.Flush (System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e) at System.IO.StreamWriter.WriteLine (System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e) at System.IO.TextWriter SyncTextWriter.WriteLine (System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e) at System.Console.WriteLine (System.Console, Version=4.1.2.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a)

Should we ignore this or don't use console class in Azure function?

CodePudding user response：

This happens when the console window has been closed, or if the console output has been redirected to a file or other stream.

In azure functions, you should not use the Console.WriteLine. instead, you should use ILogger to write logs. you can write logs like log.LogInformation("Name: " list.Count());, this will write output to the Azure Functions runtime log. you can also view logs in the azure portal.

Edit: As @Fildor suggested in comment, you could use log.LogInformation("Name: {count}", list.Count());