How to install .NET Core SDK on Ubuntu 22.04

wget https://packages.microsoft.com/config/ubuntu/22.04/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
sudo dpkg -i packages-microsoft-prod.deb
rm packages-microsoft-prod.deb
sudo apt-get update && sudo apt-get install -y dotnet-sdk-7.0

Source for these commands: Microsoft documentation

Posted by Uli Köhler in C#, Linux

How to fix .NET Core: Could not execute because the application was not found or a compatible .NET SDK is not installed.


You are trying to run a .NET core command using e.g.

dotnet new console

but you see this error message:

Could not execute because the application was not found or a compatible .NET SDK is not installed.
Possible reasons for this include:
  * You intended to execute a .NET program:
      The application 'new' does not exist.
  * You intended to execute a .NET SDK command:
      It was not possible to find any installed .NET SDKs.
      Install a .NET SDK from:


You didn’t install a .NET Core SDK, only the .NET Core host.

Install the SDK by using e.g. (this command works on Debian & Ubuntu)

sudo apt -y install dotnet-sdk-5.0

You might need to select the correct version (5.0 in this example).

Posted by Uli Köhler in C#

C# minimal program that shows a message popup dialog

This program just shows a message box and exits:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace MinimalMessageBoxProgram
    class MinimalMessageBoxProgram
        public static void Main(string[] args)
            MessageBox.Show("This is the minimal text shown in the message dialog.");


Posted by Uli Köhler in C#

How to create filename containing date/time in C#

In datalogging, often you have to create a new log file once you start to log data.

In most cases, it’s convenient to include the current date and time in the log file. Here’s how you can do that in C# without using external libraries:

string filename = String.Format("Temperature logging {0}.csv",
                                DateTime.UtcNow.ToString("yyyy-MM-dd HH-mm-ss"));

This will create filenames like

Temperature log 2020-06-17 22-37-41.csv
Temperature log 2019-12-31 00-15-55.csv

Note that if you use another Date/time format, you need to avoid special characters that must not occur in filenames. The rules for which filename is correct are much easier on Linux than on Windows, but since you should be compatible with both operating systems, you should always check the Windows rules.

These characters are forbidden for Windows filenames:


The date-time format we used above, yyyy-MM-dd HH-mm-ss is specially crafted in order to avoid colons in ISO-8601-like date/time formats such as 2020-04-02 11:45:33 since colons would be illegal in Windows filenames. yyyy-MM-dd HH-mm-ss only contains spaces and minus (-) characters in order to avoid any issues, now and in the future.

Posted by Uli Köhler in C#