Many VBA techniques look perfectly reasonable when you’re building a macro for yourself.
The problem is that production environments are rarely as simple as development environments.
I’ve worked on VBA projects where a macro ran flawlessly for months, only to start failing when another team used it, when workbook structures changed, or when larger datasets appeared.
What surprised me most was that the root cause usually wasn’t a complicated bug.
It was a coding practice that looked harmless at the beginning.
Here are some of the VBA habits I see most often that work during development but create maintenance and reliability problems in production.
Contents
- The Macro Worked Until Someone Clicked a Different Sheet
- The Small Dataset That Became a Large Dataset
- Error Suppression That Hid the Real Problem
- The Configuration Layer That Saved Future Maintenance
- The Shortcut That Made Future Changes Expensive
- Why These Problems Rarely Appear During Development
- Conclusion
The Macro Worked Until Someone Clicked a Different Sheet
One of the most common production failures comes from relying on ActiveSheet, ActiveWorkbook, or Selection.
During development, the developer controls the environment. The correct workbook is open. The correct sheet is active. The expected cells are selected.
In production, those assumptions disappear.
A user opens another workbook.
A report runs while a different sheet is active.
A second macro changes the active worksheet before the current process finishes.
Suddenly, data starts being written to the wrong location.
The code itself hasn’t changed.
The environment has.
Instead of relying on whatever Excel considers “active,” I prefer explicit references.
targetSheet.Range("A1").Value = reportDate
The extra typing may seem unnecessary, but production code benefits from predictability far more than convenience.
The Small Dataset That Became a Large Dataset
Many VBA procedures are tested with a few dozen rows.
Production systems often deal with thousands.
I frequently see code that loops through cells one at a time because performance isn’t noticeable during development.
For Each cell In Range("A1:A50000")
cell.Value = Trim(cell.Value)
Next cell
This may appear acceptable when testing with twenty rows.
Once real business data arrives, execution times can become a serious issue.
The lesson isn’t that loops are bad.
The lesson is that testing conditions rarely match production conditions.
Whenever I build automation expected to grow over time, I evaluate performance before users complain rather than after.
Many production issues are really scaling issues disguised as coding issues.
Error Suppression That Hid the Real Problem
Few VBA statements have caused more long-term trouble for me than this one:
On Error Resume Next
I understand why developers use it.
It makes development easier.
It allows execution to continue.
It removes annoying interruptions.
The problem is that it often removes visibility as well.
I once reviewed a process that had been silently skipping failed workbook operations for weeks because errors were being ignored.
Management assumed the reports were correct.
The macro appeared successful.
The data was wrong.
The failure wasn’t the workbook operation.
The failure was that nobody knew it had failed.
Today, I treat error suppression as a temporary tool for very specific situations, not as a default design pattern.
The Configuration Layer That Saved Future Maintenance
One lesson I learned after maintaining VBA projects for several years is that business rules change much more often than code.
The macro itself may remain stable for years.
The things around it rarely do.
Folder locations change.
Worksheet names change.
Output file names change.
Departments request new report formats.
Many VBA solutions fail not because the automation logic is wrong, but because important settings are buried throughout the code.
For example, I often inherit projects containing dozens of statements like this:
Sheets("Monthly Report")
or
reportPath = "C:\Reports\2025\"
The code works perfectly.
The maintenance process does not.
When a change request arrives, developers must search through the project and hope they find every affected location.
After encountering this problem repeatedly, I started separating configuration values from business logic whenever I expected future changes.
Sometimes that means keeping settings in a dedicated worksheet.
Sometimes it means storing them in constants.
Sometimes it means reading them from a configuration table.
The exact implementation matters less than the principle.
The important thing is knowing where business-controlled values live.
When someone asks, “Can we change the output folder?” or “Can we rename the report sheet?”, I want a clear answer.
I don’t want to search through hundreds of lines of VBA hoping I didn’t miss something.
Production systems rarely stay static.
The VBA projects that survive long term are usually the ones where future changes were expected from the beginning.
What looks like extra design work today often becomes a major maintenance advantage a year later.
The Shortcut That Made Future Changes Expensive
Many VBA solutions are optimized for getting a result quickly.
That’s understandable.
Business users usually want answers today.
However, I have repeatedly seen short-term shortcuts become long-term problems.
Examples include:
- Extremely long procedures
- Repeated copy-and-paste logic
- Multiple responsibilities inside one macro
- Business rules scattered throughout the project
These decisions save time initially.
They become expensive when requirements change.
A new report field appears.
A calculation rule changes.
A department requests a variation of the process.
Suddenly every modification requires updating code in multiple locations.
The original automation still works.
Maintaining it becomes the challenge.
Production reliability is often determined less by how quickly code was written and more by how easily it can be modified later.
Why These Problems Rarely Appear During Development
The biggest reason these practices survive is simple.
Development environments are controlled.
Production environments are not.
During testing:
- Data is clean
- Workbooks are predictable
- Users follow instructions
- File structures remain unchanged
Production environments introduce:
- Unexpected data
- Human mistakes
- Process changes
- New requirements
- Larger workloads
Most VBA failures aren’t caused by syntax mistakes.
They’re caused by assumptions that were never challenged before deployment.
The code passes testing because testing doesn’t fully reflect reality.
Conclusion
The VBA practices that cause the most production issues are rarely the ones developers worry about.
The dangerous ones are often the habits that seem completely reasonable when building a quick solution.
Reliance on active objects, performance assumptions, hidden errors, hardcoded values, and short-term shortcuts can all work perfectly during development.
The problem appears later, when the workbook becomes part of a real business process.
If you’re building personal tools used only by yourself, these trade-offs may be acceptable.
If you’re building automation that other people will depend on, designing for maintenance and reliability from the beginning is usually worth the extra effort.