How to handle scenarios where multiple users are processing the same file at the same time

I have a button on MS access form which when clicked, goes to a network drive and reads a json file and process it. This form will be used by multiple users at the same time. I need to handle scenarios where if multiple user clicks on the button simultaneously should not lead to error. Not more than 1 user should process the json file at the same time. Only 1 user should have access to processing the json file at a time. Can anyone suggest some ways to handle such scenarios. Programming language used is VBA. Also has access to SQL server.