All of the following criteria must be met

• All Requirements must be installed.
• Changed the title so that it doesn't just says "[Bug]: "
• I have searched the GitHub issues for my bug, even in the closed issues.

All of the following are optional to answer

• Tried reinstalling the Game.
• Tried reinstalling MelonLoader.
• Tried restarting PC.
• Was able to see the Start Screen.

Describe the issue.

after the latest update of Schedule I, MelonLoader no longer starts during the game, I also thought that maybe I had to download the latest version of Melonloader, but when I try to install/update it, an error appears saying that the application must be closed, even though the game has never been started, I also tried to start Melonloader immediately after restarting, but this error always appears, this prevents me from deleting/downloading/updating it because this inexplicable error appears, it had never happened to me in the past,

Did you attach your log file?

No, I could not find a log file at {Game_Directory}\MelonLoader\Latest.log

Try to kill the Cpp2IL.exe process through the Task Manager, or use File Locksmith from Power Toys by calling it on the folder with the game (you may need to check with administrator rights in the upper right corner of the program)

@OldRazeJedy > Try to kill the Cpp2IL.exe process through the Task Manager, or use File Locksmith from Power Toys by calling it on the folder with the game (you may need to check with administrator rights in the upper right corner of the program)

I can't find the process you mention in your answer, then I tried with PowerToys to unlock/lock Locksmith files but even with the administrator it told me "no results"

The Installer has a known issue where it overrides the correct Error Message with this.
Either update to the development nightly build of Installer v4.2.1 at https://nightly.link/LavaGang/MelonLoader.Installer/workflows/build/development or wait for it to officially release