When Steam attempts to validate game files, it checks if the files on your computer match the files stored on Steam's servers. If the files don't match or are corrupted, Steam will display the "Steam files failed to validate and will be reacquired" error. This error typically occurs when:
If the same validation failure happens repeatedly, try these steps in order:
Overzealous security software might block or delete game files it incorrectly identifies as threats.