Replacing old business software without bringing work to a halt

Many businesses still run on software written a long time ago. Maybe it's a desktop program built on technology that's no longer supported. Maybe it's a database only one person understands, or a system whose original developer can't be reached any more.

It still works, mostly. The worry is that one day it won't, and there's no plan B.

Moving off old software while the business carries on is a real project. Rushed, it's one of the riskiest things a company can do. Done in small, careful steps, it's very manageable.

Signs it's time to act

• The software, or the Windows version or database it runs on, no longer gets security updates.
• Only one person, inside or outside the company, can make changes to it.
• It can't be used safely from outside the office, so work stops when people travel.
• New needs are handled in Excel, because changing the system feels too risky or too slow.
• There are backups, but nobody has ever tried restoring one.

Find out everything the old system does

Old software usually holds years of business rules. There are special discounts for certain customers, the way amounts are rounded, how invoice numbers run, and the report someone in accounts relies on every month. Hardly any of this is written down. If the new system misses one, people discover it on the first day, usually at the worst possible moment.

So before designing anything new, make a list of what the old system really does:

• Every screen and report: who uses it, how often and why.
• Every calculation and rule, checked with real examples rather than guessed.
• Every way information gets in and out: imports, exports, printouts, emails, other programs.
• Anything that runs by itself, like month-end routines or overnight jobs.
• The workarounds people use where the system falls short. These count as requirements too.

Replace it one piece at a time

The riskiest approach is to build the whole new system separately and switch everything over in one weekend. Every unknown problem then shows up on the same Monday morning. Going piece by piece spreads the risk out:

1. 01Pick a first piece that's useful and fairly self-contained. For example, handling enquiries, the reports, or one department's work.
2. 02Build that piece in the new system, and link it to the old one so both stay up to date where needed.
3. 03Move only the people who use that piece. Everyone else carries on in the old system as normal.
4. 04Learn from it and adjust, then pick the next piece.
5. 05Switch off the old system when nothing depends on it any more, not on a date fixed months in advance.

Running two systems side by side takes some extra effort for a while, mostly in keeping the data matched up. That's usually far cheaper than a big switch-over that goes wrong.

Moving your data is a job of its own

Data in an old system is rarely tidy. Fields have been used for things they weren't meant for. Codes have changed meaning over the years. Duplicates have piled up. Moving it safely needs:

• A plan for where every old piece of information goes in the new system, and what to do with anything that has no obvious home.
• Clean-up rules, agreed with the people who own that data.
• A repeatable process, so the move can be practised several times before it's done for real.
• Checks afterwards, such as record counts, totals and spot checks, that someone in the business signs off.

Always keep a way back

For each piece, agree in advance what would make you go back to the old way, and how you'd do it. Keep the old system available, even if only for looking things up, until the new one has handled a full business cycle. That includes a month-end and any busy season. Confidence should come from seeing it work, not from the project plan saying so.

Why the new system is usually browser-based

Most replacements today run in a web browser, like Chrome or Edge. That brings several benefits:

• There's nothing to install on each computer.
• People can use it securely from wherever you allow.
• Updates happen once, centrally, instead of machine by machine.
• It's easier to add a portal for customers or suppliers later.

Our legacy modernization work follows this path, one piece at a time.

If you depend on a system that worries you, the first step is simply understanding what it does. Tell us about it, and we'll help you plan from there.