How to fix “The type initializer for ‘Gdip’ threw an exception” caused by the netcore framework depencency,  when you run a Xaf Blazor App on ubuntu linux 18.04

How to fix “The type initializer for ‘Gdip’ threw an exception” caused by the netcore framework depencency, when you run a Xaf Blazor App on ubuntu linux 18.04

If you are running Xaf Blazor in ubuntu 18.04 you might have seen the following exception

The type initializer for ‘Gdip’ threw an exception.
at DevExpress.ExpressApp.Actions.ActionBase.OnHandleException(Exception e) at DevExpress.ExpressApp.Actions.ActionBase.ExecuteCore(Delegate handler, ActionBaseEventArgs eventArgs) at DevExpress.ExpressApp.Actions.PopupWindowShowAction.DoExecute(Window window) at DevExpress.ExpressApp.Actions.PopupWindowShowAction.DialogController_Accepting(Object sender, DialogControllerAcceptingEventArgs e) at DevExpress.ExpressApp.SystemModule.DialogController.Accept(SimpleActionExecuteEventArgs args) at DevExpress.ExpressApp.SystemModule.DialogController.acceptAction_OnExecute(Object sender, SimpleActionExecuteEventArgs e) at DevExpress.ExpressApp.Actions.SimpleAction.RaiseExecute(ActionBaseEventArgs eventArgs) at DevExpress.ExpressApp.Actions.ActionBase.ExecuteCore(Delegate handler, ActionBaseEventArgs eventArgs)

The error is caused by missing dependency, so the DotNet runtime itself will throw that exception. Also, I want to highlight that the exception is not related to XAF, you can read more about this problem here

To get the missing dependency just open a console and run the following commands

sudo apt-get update -y

sudo apt-get install -y libgdiplus






How to monitor your aspnet core application on Ubuntu Linux

How to monitor your aspnet core application on Ubuntu Linux

Here are some recommendations to host your new shiny aspnet core app on Linux in this case in Ubuntu 18.04

First, create a user with the name aspnetapp

sudo adduser myaspnetapp


after executing the command, you will have a new folder in your home directory the folder will have the same name as your username so in this case “myaspnetapp”

now let’s SSH to with the new user you just created you can do that using your favorite SSH client, for example, if you are using windows you can use putty

when you log in with the new user you will be in its home folder, now we can create a folder called app with the following command


mkdir app

your folder structure should look like this now


Now we are ready to upload the files. By now should have already compiled and publish your application to run in Linux, if you have not done that yet then you should take a look to this article

There are many options to upload a zip file but I think is the best way is to use the secure copy command from linux “scp”, I won’t explain how you should call the scp command but if you are using windows you can run that command from the WSL console and if you are using Linux the command is already built-in, anyway here is an article about it

Here I will write an example of how the scp command should look like and you adjust it to your needs

scp myaspnetapp@

so that command above will do the following, it will copy the file from the local folder to a server running on the following the IP and the folder “/home/myaspnetapp/app”

now let’s unzip the content of the folder zip with the following command



What we have done so far:

  1. We have created a user in the OS
  2. We have created a folder to host our application within the user home folder
  3. We have uploaded a zip file containing our application the folder “/home/myaspnetapp/app”


Now that the app is already in the server we need to change the permission of the folder where the app lives to 0777, you can learn more about Linux file system permissions here

Creating a service to monitor the app

The next step to monitor our app is to use systemd is an init system that provides many powerful features for starting, stopping, and managing processes.

Let’s start by creating a service file in the following path “/etc/systemd/system/”

You can do that with the following command:

sudo nano /etc/systemd/system/MyExecutableFile.service


here is how the content of the file should look like



Description=A description of your app


WorkingDirectory=/home/myaspnetapp /app

ExecStart= /home/ myaspnetapp /app/MyExecutableFile


# Restart service after 10 seconds if the dotnet service crashes:



SyslogIdentifier= MyExecutableFile





Here is a little explanation of what you might need to change if the file above

WorkingDirectory: this is the working directory, usually is the same where the app lives

ExecStart: This is the executable file how what will you write here will depend on your application if its self-contained you just need to write the name the full path of the executable file otherwise you need to write the path to the dotnet runtime and then the path to your dll as show below:

/usr/local/bin/dotnet /var/www/helloapp/helloapp.dll

RestartSec: this is the time to wait before trying to restart the app after if the process crashes

SyslogIdentifier: the app identifier for sys logs

User: this is really important since the app will run under this user privileges, so you need to make sure that the user exists and that is able to access the files needed to start the app

That is all that we need for the service file now we need to go back to the console and enable our new service, you can do that with the following command

sudo systemctl enable MyExecutableFile.service

To start and stop the service you can use the following commands

//To Start
sudo systemctl start MyExecutableFile.service

//To Stop
sudo systemctl status MyExecutableFile.service
























Install TestCafe in Ubuntu 18.04

Install TestCafe in Ubuntu 18.04

Lately, I have been playing a lot with TestCafe which is a testing tool for website, there are 2 parts of TestCafe, the first part is TestCafe studio which is a tests editor tool where you can create or edit new tests that will be eventually used in the TestCafe test runner, both TestCafe and the test runner runs on Windows, MacOS, and Linux.

So what we are going to do today is to install TestCafe on Ubuntu Linux 18.04, in this tutorial we will only install the test runner because, in the end, my main goal is to use TestCafe to emulate the load on a server, so let’s get started

First, we need to install NodeJS and NPM, this is kind of tricky depending on your OS version, for example, if you run this command :

sudo apt -y install nodejs

in Ubunto 18.04 you will end up installing NodeJS version 8 something… that’s too old for what we need to do, so first let’s install the latest version of NodeJS, in this case, this is version 12

Installing NodeJS and NPM

1) First, let’s update our repository information

sudo apt update
sudo apt -y upgrade

2) Manually add Node.js APT Repository

sudo apt update
sudo apt -y install curl dirmngr apt-transport-https lsb-release ca-certificates
curl -sL | sudo -E bash -

3) now let’s install NodeJS

sudo apt -y install nodejs

4) This step is optional, if you want to verify the versions of NodeJS and NPM you can use the following commands:

node --version
npm --version


Installing TestCafe

To install TestCafe you only need to execute one command, so here it is

npm install -g testcafe

That was easy !!!

That is everything for this post, see you!!!




Ubunto add missing resolution (18.04.4 LTS && 20.04 LTS)

Ubunto add missing resolution (18.04.4 LTS && 20.04 LTS)

1) Determine Name of Display

sudo xrandr -q

Determine Name of Display


In my case, I will add the missing resolution to the display HDMI-2 (below you can see that I highlight all the current resolutions for this display)


List of supported resolutions

 List of currently supported resolutions

2) Run command to calculate VESA CVT mode lines by given resolution

cvt 2560 1080 (in this case 2560 is my monitor width and 1080 is the hight, you should replace these values to something that match your current need)

3) Now we need to run the command “sudo xrandr –newmode” and then paste the output value from step 2, in the end, it will look like the snippet below

xrandr --newmode "2560x1080_60.00"  230.00  2560 2720 2992 3424  1080 1083 1093 1120 -hsync +vsync


Add new resolution

4) Now add the newly created mode for your display device, the structure of the command is “xrandr –addmode DisplayId Resolution”, you should replace the DisplayId for the id you got in step 1 and the resolution from what you got in

xrandr –addmode HDMI-2 “2560x1080_60.00”

Add New Resolution To Display

Add New Resolution To Display


5) Set the new resolution

Set The New Resolution

Set The New Resolution

6) So far we added the new resolution and associated it to the monitor that we want, this is not permanent it will just work until you reboot, so to make these changes permanent you need to edit your profile using the following command

gedit ~/.profile


Paste the commands from step 3 and 4 and save the file


Edit Profile To Add Resolution

Edit Profile To Add Resolution