Every legacy modernisation brief I have read in the UAE opens the same way. There is a system, it is old, it is expensive to change, and somebody has already decided what to replace it with. The brief then asks for engineers who know the new thing. That request is the problem, and it is why so many of these projects spend a year producing something technically excellent that operations refuses to switch to. The order below is the one I would run if I were starting again, and the first four steps happen before you open a single requisition.
Why These Projects Stall, and Why It Looks Like a Hiring Problem
A legacy system that has been in production for years is not just code. It is code plus a decade of accommodations: the report that rounds a particular way because finance asked for it in 2019, the import that tolerates a malformed reference because a supplier never fixed their export, the overnight batch whose completion time three downstream processes silently depend on. None of this is in the documentation. Much of it is not in anyone’s head either. It is in the behaviour.
When a modernisation team is staffed around the target stack, nobody on it is accountable for finding that behaviour. The system gets rebuilt from the specification people can articulate, which is the visible fraction. Then cutover arrives, the invisible fraction surfaces as a queue of defects, and the project enters the phase every delivery lead recognises: a long argument about whether each item is a bug the team must fix or a change request the business must fund. Projects rarely die in that argument. They just stop being worth finishing.
The fix is not a better team. It is a different sequence, with the investigation funded as its own phase and staffed with different people from the ones who will build the replacement.
💡 Our Expert Take
Watch for the brief that names the target stack in the first sentence. It almost always means the decision was made by whoever is most comfortable with that technology rather than by the shape of the problem, and it means the investigation phase has already been skipped. It is recoverable, but you have to recover it before you hire, because the moment you have six engineers on the payroll waiting for work, the investigation gets compressed into a fortnight and the project reverts to building from the articulated specification.
The 7 Steps, in Order
Step 1: Inventory the behaviour, not the code
Before anybody reads the source, write down what the system does for whom. Not modules: outcomes. Every scheduled job and what breaks if it runs late. Every report and who acts on it. Every integration and what the other side assumes. Every manual workaround the operations team has built, because each of those is a defect in the current system that somebody has already priced into their working day, and some of them must be preserved.
The method that works is interviews plus observation, not document review. Sit with the people who use the system on their busiest day of the month. Ask what they do when it misbehaves. The answers to that question are the undocumented requirements, and they are the single highest-value artefact in the whole project. Two weeks of this is cheap. Discovering the same list at cutover is not.
Step 2: Choose the migration pattern before the team shape
There are four honest options, and they imply completely different teams. Encapsulate: leave the system running and put a clean interface in front of it, so new work can be built against the interface. Re-platform: move it, unchanged in behaviour, onto supported infrastructure. Incremental replacement: stand up new services that take over one slice of functionality at a time while the old system keeps serving the rest, the approach Martin Fowler documented as the strangler fig application. Rewrite with a single cutover: build the replacement in full, switch once.
The fourth is the only one that can run for a very long time and deliver nothing until the end, which makes it the option to justify explicitly rather than default into. The broader taxonomy is worth reading before the decision is made: AWS publishes a documented set of migration strategies covering retain, retire, re-host, re-platform, re-architect and replace, and naming which one you are doing forces a conversation that otherwise stays vague.
This choice determines everything downstream. Encapsulation needs integration engineers and almost no target-stack specialists. Incremental replacement needs routing, observability and dual-write expertise that a feature team will not have. If you pick the team before the pattern, you will end up doing whichever pattern that team is shaped for.
Step 3: Put a number on the cost of doing nothing
Modernisation budgets get cut because the conversation only has one number in it: what the project costs. Build the other side. The annual carrying cost of the current system is real and usually larger than people expect once it is itemised: unsupported software and the premium paid for extended support, the engineer time spent on manual processes that exist only because the system cannot do them, the delivery tax on every new feature that has to be threaded through the old architecture, the cost of incidents, and the recruitment difficulty that comes with asking people to work on it.
Itemise those with finance, not in isolation. Two numbers on a page changes the decision from “can we afford this project” to “which of these two costs do we prefer”. If you need a defensible figure for the project side, the project estimation tool gets you to a range you can argue for.
Step 4: Hire the archaeologist before the architect
Now you can open a requisition, and it should not mention the target stack. The first hire needs one demonstrable ability: taking a system they have never seen, that nobody can fully explain, and producing a written account of what it does that survives contact with reality. That is a specific and uncommon skill, it is not seniority, and it does not correlate with knowing your destination technology.
Screen for it directly. Give the candidate a genuinely unfamiliar piece of code, forty minutes and no documentation, and ask them to tell you what it does, what they are unsure about, and what they would check first. Strong candidates spend most of that time on the second and third parts. Weak candidates produce a confident summary with no stated uncertainty, which is exactly the failure mode that kills modernisation projects. The interview question library has variants of this exercise, and it generalises: the same screen works for the data person you need alongside them.
Only after the inventory exists do you hire for the target stack, and by then you know precisely what you are hiring for. If the destination is cloud-native, cloud application development in the UAE is a well-supplied market in Dubai; if it is a rebuilt line-of-business application, custom software development teams are straightforward to assemble. The scarcity is never there. It is in step 4.
💡 Our Expert Take
The best archaeologists we place are rarely the people with the most impressive stack list. They are often engineers who spent years maintaining something unloved at a bank, an insurer or a logistics business, who have read more code than they have written, and who are visibly unbothered by not knowing something yet. They interview badly against a standard algorithm screen and brilliantly against a read-this-and-tell-me-what-it-does screen. If your process is the former, you will filter out the exact profile this project needs.
Step 5: Freeze the definition of parity, in writing
Parity is the word that quietly destroys these projects, because everyone uses it and nobody defines it. Write the definition down and have it signed by whoever owns the business process, before development starts. Three lists: behaviour that must be reproduced exactly, behaviour that must be reproduced in outcome but may change in form, and behaviour that is explicitly being dropped.
The third list is the one that gets skipped, and it is the most valuable. A modernisation project is the only realistic opportunity to remove accumulated behaviour nobody wants, but removal has to be a decision taken in advance by a named person, not a discovery made at cutover by an angry user. Put dates and owners against the third list and circulate it widely enough that objections arrive early.
Step 6: Build the test harness against the old system
While the legacy system is still running, capture its behaviour as executable tests. Feed the same inputs to both systems and compare outputs, and keep doing it for the whole delivery phase. This is the mechanism that turns the behaviour inventory from a document into a guarantee, and it is the step most often cut when the schedule tightens.
It needs dedicated test engineering, which is why step 2 matters: the budget for it has to be in the plan from the start rather than borrowed from a shared quality pool halfway through. Where there is a database at the centre of the system, and there usually is, the comparison has to extend to data: row counts, reconciliations and the specific aggregates the business actually looks at. A database specialist on the team for this phase pays for itself the first time a migration script silently drops a category of record.
Starting one of these? Get the sequence right before you hire.
We help UAE businesses scope the investigation phase, choose the migration pattern and then staff each phase with the right profile. Custom software in the UAE | Platform engineers | Delivery services
Start with step 1Step 7: Staff the rollback, not just the cutover
Every plan has a cutover runbook. Fewer have a rollback runbook, and almost none have a named person whose job on the day is to decide whether to use it. Those are different roles: the person leading the cutover is invested in it succeeding, which is exactly why they should not be the one holding the reverse gear.
Three things make this real rather than ceremonial. Rehearse the rollback in a non-production environment, with timings, so you know whether it takes twenty minutes or six hours. Agree the trigger conditions in advance and in numbers, so the decision is a measurement rather than a debate at two in the morning. And keep the old system funded and operable until the new one has survived a full business cycle, including the month-end or quarter-end that exercises the paths nobody tests.
The hiring sequence in one table
| Step | What you decide or produce | Who you hire at this point |
|---|---|---|
| 1. Behaviour inventory | Written account of what the system does for whom | Nobody yet, use internal people plus one senior contractor |
| 2. Migration pattern | Encapsulate, re-platform, incremental or rewrite | Nobody yet |
| 3. Cost of doing nothing | Two numbers on one page, agreed with finance | Nobody yet |
| 4. Investigation | Characterised system, open questions ranked | The archaeologist, a data specialist |
| 5. Written parity | Three signed lists, including what is dropped | Product or operations owner named |
| 6. Harness and delivery | Executable comparison against the old system | Target-stack engineers, dedicated test engineering |
| 7. Cutover and rollback | Rehearsed reverse path with numeric triggers | Operations capacity, a named rollback owner |
FAQ: Staffing a Legacy Modernisation Project
Should I hire for the old stack or the new one when modernising a legacy system?
For the first phase, hire for the ability to characterise unfamiliar code rather than for either stack. The scarce skill in a modernisation project is reading a system nobody can explain and writing down what it actually does, under uncertainty, without breaking it. Target-stack expertise is widely available in Dubai and can be added once the behaviour inventory and the migration pattern are settled. Hiring the target-stack specialist first usually produces a beautiful new system that does not do what the old one did.
How long does a legacy modernisation project take in practice?
It depends almost entirely on the pattern chosen, not on the size of the codebase. Encapsulating a system behind an API and leaving it running is measured in weeks. Re-platforming without changing behaviour is measured in months. Incremental replacement, where new services take traffic one slice at a time while the old system keeps running, is measured in quarters but ships value continuously. A full rewrite with a single cutover is the only option that can run for years and deliver nothing until the end, which is why it is the pattern to justify rather than assume.
What team size does a modernisation project need in Dubai?
Smaller than most plans assume at the start, and larger in the middle. Phase one needs two or three people who can investigate: someone senior enough to characterise the system, someone who knows the data, and a product or operations person who can confirm what behaviour is load bearing. The delivery phase needs the engineers for the target stack plus dedicated test engineering, and the cutover phase needs operations capacity that is not also writing features. Staffing the full delivery team during the investigation phase is the most common way to burn a budget before anything is known.
Why do legacy modernisation projects fail even with a strong team?
Because parity was never defined. A legacy system that has run for years accumulates behaviour that nobody documented and users silently built processes around: a report that rounds a particular way, an export that tolerates a malformed field, a batch job whose timing something downstream depends on. If parity is not written down and signed before development starts, every one of those becomes a defect discovered at cutover, and the project stalls in an argument about whether it is a bug or a change request.
Run step 1 before you write the job description.
Tell us what the system does and who depends on it, and we will tell you which profile to hire first and which phase to fund. Cloud application development | Database specialists | More delivery guides
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