Structured error trapping with OnError

Expert

Build bulletproof scripts by combining OnError [ Go to [label] ] with Get(LastError) lookup tables.

What you'll learn

How to redirect script flow on error using labels
How to capture and translate error codes with Get(LastError)
How to clean up partial changes before exiting on error

The default OnError [ Stop ] behavior halts a script and shows the user a raw error dialog. Switching to OnError [ Go to [label] ] lets you capture the error code, translate it into plain language, clean up any half-completed work, and exit gracefully.

Stuck is a valid status

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Redirect errors to a handler label

Place OnError [ Go to [label] ] at the top of your script. Add a label like "::Error" near the bottom. FileMaker jumps to that label whenever a script step returns a non-zero error code.

FileMaker Script

# Top of script
Set Error Capture [ On ]
OnError [ Go to [::Error] ]

# ... main script logic ...

Exit Script [ Text Result: "success" ]

::Error
Set Variable [ $errorCode ; Value: Get ( LastError ) ]
Show Custom Dialog [ "Operation failed (code " & $errorCode & ")" ]
Exit Script [ Text Result: "error" ]

Designing FileMaker scripts for Data API calls Passing complex data via JSON script parameters