Why Your Macros Fail on Another Computer – and How to Prevent It

Avoid environment-dependent breakage.

Usual suspects

• Missing add-ins or references
• Different Office bitness (32/64-bit)
• File paths and network drives
• Locale-dependent parsing (dates, decimals)

Hardening checklist

• Use ThisWorkbook.Path not ActiveWorkbook.Path
• Handle missing references gracefully
• Prefer late binding for Office apps (CreateObject("Outlook.Application"))
• Use PtrSafe and Declare PtrSafe for 64-bit APIs