some extra trouble shooting added

Author: fjnn

_pages/shared_pages/ros-related-pages/simulation-gazebo.md

@@ -285,4 +285,43 @@ We can add some items by just adding items as we included the sun and the ground
 You can change the position and orientation of any object which you have added with the `<pose>x y z roll pitch yaw</pose>` tag. Probably the easiest is to design the world in Gazebo and directly save there.
 
 {: .notice--info}
-Don't forget to add your /world folder directory in the **setup.py**
+Don't forget to add your /world folder directory in the **setup.py**
+
+# Troubleshooting
+
+## Cannot do "sudo apt update"
+The problem is either about your internet connection or ROS 2 GPG Key. First make sure that you have internet. Afterwards open a new terminal and paste this command: `sudo curl -sSL https://raw.githubusercontent.com/ros/rosdistro/master/ros.key -o /usr/share/keyrings/ros-archive-keyring.gpg`
+
+
+Now you can:
+```
+sudo apt update
+sudo apt upgrade
+```
+
+## Getting "cache lock" error
+It might be your **lock-frontend** process blocking the system. Find its process id (PID) and kill the process:
+
+```
+sudo lsof /var/lib/dpkg/lock-frontend
+```
+
+Use this PID and replace \<PID\> in the next command:
+
+```
+sudo kill -9 <PID>
+```
+
+## Robot looks weird on Gazebo
+That is such an annoying problem but let's try. Probably your ros2-control packages are outdated and ´sudo apt upgrade´ cannot fix them - IDK why. We can remove them and reinstall them. Try using these commands:
+
+```
+sudo apt remove  ros-foxy-ros2-control*
+sudo apt remove ros-foxy-gazebo-*
+sudo apt update
+sudo apt upgrade
+sudo apt install ros-foxy-ros2-control*
+sudo apt install ros-foxy-gazebo-*
+```
+
+and then restart the VM.