Fortunately, this error is relatively easy to fix. Follow the solutions below on what you need to do.

1. Reboot Nintendo Switch console.

   The software on Nintendo Switch is generally stable and in most cases, a simple reboot fixes problems. Make sure to restart your Switch.
   To turn off the console, just press and hold the Power button for about 3 seconds. Once the Power options appear, select Power Off. Turn the console back on again and check for the problem.
   Alternatively, you can force reboot the console by pressing and holding the Power button for about 12 seconds. This is useful if the Switch is unresponsive or does not respond to any input.

2. Verify software and game are up-to-date.

   In most situations, your console should download game and system updates automatically when connected to the internet. However, you can manually check for game or system updates whenever you like. 
   To check for a system update:
   -Make sure that your Nintendo Switch is connected to the internet.
   -Go to the Home Menu.
   -Select System Settings.
   -Select System.
   -Select System Update.
   -Wait for a few moments to allow the system to check for new software version.
   -If an update is available, the download process will begin automatically.
   To look for an update for a game or software manually:
   -Make sure that your Nintendo Switch is connected to the internet.
   -Go to the Home Menu.
   -Select the icon for the software you wish to update without starting the game or application.
   -Press the + Button or – Button, then select Software Update, followed by Via the Internet.

3. Remove and reinsert the game card.

   If you’re having an issue when playing using a game card only, try removing and reinserting it. When trying to remove the game card, make sure that you’re not in the middle of the game by going to the Home menu first. Better still, turn off the console entirely before physically taking out the game card.

4. Test different game cards.

   To continue troubleshooting for a possible game card issue, try to see if the Software was closed error happens with other game cards. If it continues with a new card, it may be a system-related problem. Otherwise, it may only be a game card-specific issue.
   If the error shows on multiple game cards, your console may need to be repaired.

5. Check for corrupted data.

   You can tell your Switch console to scan its system for any corrupted data. Here’s how:
   -Go to the Home Menu.
   -Select System Settings.
   -Scroll through the options on the left and select Data Management.
   -On the right-hand side, select Software.
   -Then, select the software you would like to check.
   -Select Check for Corrupt Data.

6. Remove and reinstall game.

   If the error only occurs when using a software or game that you downloaded (not using a game card), try to see if deleting it from the system helps.
   To delete a software:
   -Make sure that you check for system updates first.
   -Go to the Home Menu.
   -Select System Settings.
   -Scroll through the options on the left and select Data Management.
   -On the right-hand side, select Software.
   -Then, select the software you would like to delete.
   -After deleting a software, restart the console before downloading it again.
   -Check for the error.

7. Restore software to defaults (Factory reset).

   If none of the solutions above has helped, consider wiping the console with a factory reset. This can be an effective solution to do if the cause is due to an unknown software bug.