Many Singapore SMEs delay replacing a slow 10-year-old desktop accounting/inventory server or a tangle of 40 Excel workbooks because they are terrified of losing historical customer records, open invoices, or stock balances during the switch. That fear is valid when a vendor treats data migration as a last-minute CSV import on launch morning.
When scoping a move to custom cloud software—or transitioning into integrated platforms like SumBook, PeopleBook, StockBook, and LeadPlus—run these seven legacy data migration checks weeks before go-live.
1. Separate “Live Cutover Data” from “Read-Only Historical Archives”
Why it matters: Trying to migrate every single line item of 12 years of closed delivery orders from a legacy FoxPro or SQL database into your new transactional tables balloons migration cost and pollutes clean data structures.
What to do: Migrate (a) active master records (Customers, Suppliers, SKUs, Staff), (b) all open/unpaid invoices, purchase orders, and leave balances, and (c) 12–24 months of summary history—while storing older 7-year statutory records in a searchable read-only archive table.
2. Deduplicate and normalise master keys (UEN, Mobile, Email, SKU Code) before import
Why it matters: Legacy spreadsheets routinely contain three variations of the same client (ABC Pte Ltd, A.B.C. Private Limited, ABC P/L) and phone numbers formatted in six different ways. Importing dirty master lists breaks your CRM/accounting integrations and AI tools.
What to do: Run an automated staging deduplication script that merges duplicate entities under a single canonical primary key and preserves the legacy ID in a legacy_ref_id field for lookup.
3. Map field types, character encodings and Singapore formatting rules explicitly
Why it matters: Old desktop systems often store dates in ambiguous MM/DD/YY formats, strip leading zeros from Singapore postal codes (turning 049315 into 49315), or garble Mandarin/multilingual product descriptions due to non-UTF-8 encoding.
What to do: Build a written Field Mapping Specification verifying ISO dates (YYYY-MM-DD), 6-digit string postal codes, UTF-8 text encoding, and exact decimal rounding rules.
4. Reconcile opening financial, stock and leave balances to the exact dollar and unit
Why it matters: If your old system says you have 420 units of SKU-104 and S$84,320.50 in Accounts Receivable at 5:00 PM Friday, and your new cloud system shows 412 units and S$81,900.00 on Monday morning, staff will immediately lose trust in the new software.
What to do: Generate automated pre-migration and post-migration control totals (Total AR, Total AP, Total Stock Valuation by Warehouse, Total Leave Balances) and require 100% reconciliation sign-off.
5. Run at least two full Trial Migrations into the UAT environment
Why it matters: You only discover edge cases—like negative stock rows, orphaned credit notes, or 200-character address strings—when you run the import script against the real production dataset.
What to do: Execute Trial Migration #1 four weeks before launch for User Acceptance Testing (UAT) with real company data, fix all rejected rows, and run Trial Migration #2 one week before launch.
6. Define the “Data Freeze Window” and weekend cutover runbook
Why it matters: If sales staff keep issuing invoices in the old desktop software on Saturday afternoon while engineers are migrating Friday night’s database dump, Saturday’s transactions get lost.
What to do: Set a formal Data Freeze Window (e.g., Friday 6:00 PM SGT), switch the legacy system to read-only mode during that window, run the final delta migration, verify control totals on Saturday, and open the new cloud portal on Monday morning.
7. Maintain a 14-day parallel verification & instant rollback plan
Why it matters: During the first two weeks after cutover, finance or warehouse staff will inevitably want to look up an old closed job to compare how the legacy system calculated a number.
What to do: Keep the legacy software accessible in strictly Read-Only mode for 14 to 30 days after launch so staff can cross-check historical records without accidentally entering new transactions in the old system.
Legacy-to-Cloud Data Migration Verification Matrix
Require these four reconciliation sign-offs during your cutover weekend:
| Data Domain | Active Cutover Scope | Reconciliation Control Check | Sign-Off Owner |
|---|---|---|---|
| Customers & Suppliers | Deduplicated master list + contacts + credit terms | Exact active entity count & legacy_ref_id lookup |
Sales & Procurement Lead |
| Open AR / AP & Accounting | All unpaid invoices, credit notes & trial balance | Total AR & AP match legacy aged report to S$0.01 | Finance Manager / Director |
| Inventory & Batch Stock | On-hand, reserved & batch expiry per warehouse | 100% unit count & FIFO valuation match | Warehouse / Ops Manager |
| HR, Leave & Payroll History | Active employee profiles, leave balances & rosters | Exact annual/medical leave balance per staff ID | HR Manager |
Migrate from spreadsheets or legacy servers without operational downtime
At W Creates Digital, our cloud and software engineering team plans and executes structured data migrations into custom web applications and our SumBook, PeopleBook, StockBook, and LeadPlus platforms. Contact our Singapore team to plan a safe migration roadmap.