Cannot solve error "Login Failed: startIndex cannot be larger than length of string"

[Chris Tucci]

I am trying to troubleshoot using a piece of software that the developer no longer provides support for. When the application opens, it provides a login prompt to access the main application interface. These users for the program are stored in a 'loginusers' table in the mysql database.

Upon attempting to login, I get the error shown below. What is interesting is, it seems to be accessing the 'loginusers' table okay because if I enter an incorrect username, I get a different "invalid login" error that the username isn't found. If I enter a valid username that is in the table, I get the below error regardless of if I enter the correct password or not. So it seems something is going on between the program verifying the username is valid and checking if the password entered matches that username.

Any ideas on how to fix or at least find out more info on where this error is coming from?

Error Message Image: