From GameWatcher: "Apex Legends is no stranger to technical issues of all sorts, but it seems the recent invalid game executable error is more pervasive than we've been used to. Namely, the r5apex.exe error makes you unable to run the game, which is obviously a major problem.
Here, we'll try to explain what this particular error does and what some potential fixes might be. Having said that, there is some conflicting info available online, so be sure to take all of this with a grain of salt. Can't hurt to try, however."