LegacyLeaps vs Manual Migration

Time, cost, and what you'll miss. A realistic look at what manual .xls and .mdb migration actually costs your business.

What "Manual Migration" Actually Involves

Manual migration sounds straightforward: open the file in Excel, Save As .xlsm, done. In practice, for files with any complexity at all, that's just the beginning.

A complete manual migration of a non-trivial .xls workbook with macros involves:

• Opening the file and doing a Save As to .xlsm
• Opening the VBA editor and reviewing all modules for 32/64-bit compatibility issues
• Updating every Declare Function statement with PtrSafe and changing pointer types
• Testing every macro to confirm it runs correctly
• Checking all ActiveX controls still respond to events
• Verifying all named ranges, data validation rules, and conditional formatting survived
• Checking all external references point to the right paths (especially if other .xls files also need migration)
• Testing on an actual Windows 11 machine to catch environment-specific issues
• Documenting what changed for your own records

For a simple workbook with a few macros, this might take 30 minutes. For a complex workbook built over years with interconnected modules, ActiveX forms, and external connections, it can easily take a full day — per file.

The Hidden Costs

Side-by-Side Comparison

What Manual Migration Misses

Experienced developers doing manual migration still regularly miss these issues:

1. VBA Code Hidden Behind Sheets

Event handlers in ThisWorkbook and individual sheet code modules are easy to overlook. They don't appear in the Module list in the VBA editor — you have to click each sheet object separately to find them. Missed event handlers cause silent failures that only appear when a specific user action triggers the event.

2. Deprecated Function References

VBA code in old workbooks often references DLLs, COM objects, or type libraries that no longer exist at their original paths. The references appear broken (unchecked) in the References dialog but the project still compiles and runs — until one specific code path needs that reference. Manual migration rarely catches these until something fails in production.

3. 32/64-bit Issues in Rarely-Executed Code

A manual review catches PtrSafe errors that appear at compile time. But some API calls only fail at runtime, in specific code paths that aren't tested during migration. These surface weeks or months after the migration when someone runs a function that nobody thought to test.

4. Cross-File Dependencies

A file that links to other .xls files needs all referenced files to be migrated in the right order. Manual migration often migrates files independently, breaking inter-file references in the process.

When Manual Migration Makes Sense

Manual migration is the right choice when:

• You have one or two files and unlimited time
• The files are simple (data only, no macros)
• You have an experienced VBA developer who can audit the code while converting
• You want to take the opportunity to refactor and modernize the VBA code, not just preserve it

For everything else — more than a handful of files, files with complex VBA, files your business depends on — the risk/cost profile of manual migration doesn't make sense when a tool can do it faster, more reliably, and with a documented audit trail.

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