I'm working in Filemaker 6 and am getting this error message which I suspect is related to having to many files open. But I would like to know if there is something specific that is causing this.

A Google search yields no results.

No, it means that somebody clicked the Cancel button in the Status Area, and the script still had steps to run.

This is occurring mid-run of a script. Doing some debug, it seems to occur when executing another script from within a script. It is happening intermittently from several different scripts.

I think Vaughan is probably right, but I think it might also mean that the script is being (AND CAN BE) manually canceled by the User when they hit [esc]. Adding Allow User Abort [ Off ] to all scripts will remove this possibility. I believe that a script can also be stopped via a button in a subscript with Halt Current Script attached.

Solved.

It was indeed too many files open. The scripts were calling external scripts and if that file was opened when already at the 50 file limit the script would cancel without user input.

Which version of FMP are you using? The tech specs of 8.5 state:

File size: Limited only by disk space, to a maximum of 8 TB (terabytes) on a hard disk and OS API capability.

Number of files per disk: Limited only by disk space.

Number of files open simultaneously: Up to 125 files recommended.

Number of remote users per file: Maximum of 5 concurrent client.

Number of files shared: There is no limit.

I seem to remember that for 8.5 and later there is no hard open file limit, unlike FMP 6 and earlier that had a hard limit of 50 open files IIRC.