Plesk error : Unable to open the "Updates and Upgrades" page or start Plesk Installer in CLI: Update operation was locked by another update process

When we click on Updates and Upgrades button inside tools and settings in Plesk, It gives one of the below error in the browser. 

The connection has timed out

This site can’t be reached

ERR_TIMED_OUT

If you try to run it using the command prompt, it will give you the below error.

BUSY: Update operation was locked by another update process.

Error: Unable to start Plesk Installer. The following error has occurred: Installation could not be started: another installation procedure is currently running.

The issue occurs because of an already running process for the plesk installer on the server.

Please refer to the below steps to fix the issue in Linux.

1. At first, login to server using root.
   
   
2. Find the process ID of the existing plesk installer using below command.
   
   

   ps aux | grep install | grep -v grep

3. You will get the process ID of existing plesk installer. Now, kill it using the below command.
   
   

   kill (PID of process)

4. Now, remove the psa-installer.lock file from the /tmp incase if it exists.
   
   
5. Now, run the plesk installer. It should work fine.
   
   

Please refer to the below steps to fix the issue in Windows.

1. Connect the VPS via RDP. Please refer to how to connect VPS via RDP.
   
   
2. Open the command prompt and run the below command to find the process ID
   
   

   wmic process where "caption like '%installer%'" get processId,caption

3. Once you get the process ID kill the process using below command.
   
   

   taskkill /PID 7222 /F

4. You can also find the existing plesk installation process directly from task manager. Right click on it and click end task to kill the process.
   
   
5. Now, run the plesk installer in windows. It should work fine.