How to fix
“Another instance of application is already running” error
on Windows

Hello, something happened to my apps. Every time I open, close, and then try to reopen an app, it always results in an error message that says "Another instance of Messanger is already running. You can't run two instances of the Messanger. Please quit the other instance and try again."

When using your Windows computer, you might encounter an error message saying, "Another instance of the application is already running." This issue can be frustrating, especially if you need to run multiple instances of an application or if the application seems to be stuck and won't open. This error typically indicates that the application is already active, but the system cannot recognize it properly, preventing you from launching a new instance.

Possible causes

This error can occur for various reasons. A common cause is a lingering process from a previous instance of the application that did not close properly. In some cases, background processes or services related to the application might still be running, causing the system to think that the application is already active. Another potential cause is a conflict with other software or system resources that can prevent the application from launching correctly. Corrupted application files or settings can also lead to this issue.

Potential solutions

To resolve the "Another instance of the application is already running" error, you can try several methods. These include ending the application's process, restarting your computer, updating the application, and more. Below are detailed steps for each solution.

For dealing with various Windows issues related to system file corruption, DLL errors, and more, consider using the [d1] repair and maintenance tool. This tool can help maintain your system's health and prevent similar problems in the future.

Fix 1. End the application's process

Sometimes, the application might still be running in the background even if it's not visible on your screen. Ending the application process can help resolve this issue.

• Press Ctrl + Shift + Esc to open Task Manager.
• In the Processes tab, look for the application that is causing the error.
• Select the application and click End task.
• Click on the Show hidden items (up arrow) in the system tray.
• Locate the icon of the application and double-click it to launch the app.
• See if the problem still occurs.

If this method works, you can disable the automatic startup by following fix no. 4 so you won't have to launch it from the system tray.

Fix 2. Restart your computer

Restarting your computer can clear out any lingering processes and reset system resources, which can resolve the error.

• Close all applications.
• Click on the Start menu.
• Select Restart.
• Wait for your PC to reboot.

Fix 3. Check for multiple instances at startup

Sometimes, applications are set to launch multiple instances at startup, causing conflicts.

• Press Ctrl + Shift + Esc to open the Task Manager.
• Go to the Startup apps/Startup apps.
• Disable the app's startup or any duplicate instances of the application.
• Close Task Manager and click OK.
• Restart your computer.

Fix 4. Update the application

Updating the application to the latest version can fix bugs and compatibility issues that might cause the error.

• Open the application and check for updates within its settings or help menu.
• Alternatively, visit the application's official website and download the latest version.
• Install the update and restart your computer if necessary.

Fix 5. Repair or reinstall the application

Corrupted application files can cause the error. Repairing or reinstalling the application can resolve this issue.

• Press Win + I to open Settings.
• Go to Apps and click Installed applications.
• Find the application causing the error.
• Either select the app or click on the three dots and then pick Advanced options (if available).
• Here, use the Repair feature, then try Reset.
• Finally, click the Uninstall button and then reinstall the application from the official website.

Fix 6. Repair corrupted files

Damaged files in Windows can prevent the application from launching correctly.

• Type cmd in Windows search.
• Right-click on Command Prompt and pick Run as administrator.
• User Account Control window will show up - click Yes when prompted.
• Then, copy and paste the following command, pressing Enter after:
  sfc /scannow
• Wait till the scan is finished. If Windows finds system file integrity violations, it will attempt to fix them. After this, use the set of the following commands, pressing Enter each time:
  DISM /Online /Cleanup-Image /CheckHealth
  DISM /Online /Cleanup-Image /ScanHealth
  DISM /Online /Cleanup-Image /RestoreHealth
  
• (Note: if you get an error executing this last command, add /Source:C:\RepairSource\Windows /LimitAccess to it and try again).
• Close down the Command Prompt and restart your computer.

Fix 7. Perform a Clean Boot

A clean boot starts Windows with a minimal set of drivers and startup programs, helping to identify if a background application or service is causing the error.

• Type msconfig in the Windows search box and press Enter.
• Pick the Services tab.
• Mark Hide all Microsoft services and select Disable all.
• Select the Startup tab and click Open Task Manager.
• In the Task Manager, right-click on each of the items and select Disable, then close the Task Manager.
• Go to the Boot tab, mark the Safe Boot option, then click Apply and OK.
• On the System Configuration window, click OK and restart your computer.
• If the error does not occur, re-enable services and startup items one by one or in groups to identify the cause.