This is a system message, which you can not customize.
As a developer, you need to understand what is causing this error so you can inform your users why it is occurring, but more importantly block out the user's access in the system so they never get this error to begin with.
You can get this error for a number of things, so it's difficult to tell you why this is popping up.
1) You've disabled a privilege set from running scripts.
2) The user is on a layout that has records they can not access (and are trying to access).
3) The user is trying to go to a layout that they are restricted from accessing.
There are some warning that I have not found in the list of "ErrorCodes" from FileMaker, which I need to translate to the end user.
Your access privileges to not allow you to perform this action.
What better way to change this message?
Trap error messages
Test for errors and when found, ignore them or respond to them.
It's your script so you'll know what sort of errors to expect and how to handle them.
You can either code around the error by doing something more for the user or you may show a dialog. It could ask them to provide info with buttons for options or it could just say, "can't proceed". In some cases, ie, 101 error at the end of a loop of records, you want to ignore them.
In cases where it is simply a data access issue I use "beep" as a response. Most people know when they are rummaging in the wrong area so they don't need a lot of information. It's easier than putting the error message into words and has the same Pavlovian effect. In some cases, if the beep is in a loop I can include a counter. If the user goes past beep too often I'll throw a custom dialog, something along the lines of "take your hands off the mouse, go home, lie down"
Set Error Capture [off].
I translate to portuguese the messages, but, forget this. Thanks Malcolm.