ERP Data Migration Checklist: Best Practices for Success

An ERP implementation lives or dies by its data. You can select the perfect software, but if the data fueling it is corrupt, incomplete, or poorly mapped, the project is destined for failure. For IT Directors and ERP Program Leads, the migration of historical and transactional data is often the single highest-risk component of the entire implementation. It’s not just a technical "lift and shift"; it's a complex business transformation process.

This guide provides a tool-agnostic, phased ERP data migration plan to manage that risk, ensuring data integrity from your legacy system to your new cloud ERP. We'll cover the complete migration checklist, from initial scoping and mapping to final cutover and validation.

Phase 1: Strategy and Scope Definition

Before a single byte is moved, you must establish the rules of engagement. This initial phase is about building the right team and, most importantly, deciding what data truly matters to the business. A common failure is attempting to migrate everything, which introduces unnecessary risk, cost, and complexity to the data migration project.

Assemble Your Data Migration Team

This isn't just an IT task. Your migration team must be cross-functional, including a project manager, IT specialists, and data owners from key departments (e.g., finance, supply chain). Business users are critical because they understand the context and business rules of the data. For example, the finance team must define how "customer" data from three legacy CRMs maps to a single "customer" field in the new ERP, and they must be the ones to sign off on the result.

Audit and Profile Legacy Data

You cannot migrate what you don't understand. Use data profiling tools to analyze your legacy systems and identify the structure, quality, and completeness of your data. This audit will uncover hidden problems like duplicate records (e.g., "ABC Inc." vs. "ABC, Inc."), orphaned records (e.g., invoices without a customer), and data that violates new business rules. Using standard data profiling techniques is essential to scope the cleansing effort and prevent "garbage in, garbage out."

Define Data Migration Scope (What Not to Migrate)

This is a business decision, not a technical one. Actively decide what data to exclude from the migration. For instance, should you migrate 10 years of historical sales transactions, or just the last three? Migrating excessive historical data clutters the new system and extends cutover time. A common strategy is to migrate all master data (Customers, Vendors, Items) but only open transactional data (Open POs, Open Invoices) and historical summaries, keeping detailed archives in a separate data lake or data warehouse.

Establish Data Governance and Quality Standards

Define what "good" data looks like in the new ERP system. This means setting clear data quality metrics before migration begins. For example, a quality rule might be "Every customer record must have a valid email address and tax ID," or "No product can be 'active' without a cost and a price." These standards form the basis for your validation scripts later and ensure you are improving data quality, not just moving a mess. This is a core component of broader IT and data services that support long-term data integrity.

Phase 2: Design, Mapping, and Cleansing

With your scope defined, the technical work begins. This phase involves creating the detailed blueprint for the migration, mapping source fields to target fields, and performing the critical work of cleaning the data. This stage is meticulous and iterative, forming the engine of the entire migration project.

Technical Design and Tool Selection

Choose your data migration approach and tools. Will you use the ERP vendor's built-in tools (like data import wizards), a third-party ETL (Extract, Transform, Load) platform, or custom-built scripts? For complex migrations with multiple legacy systems, a dedicated ETL tool is often recommended as it provides better transformation logic and error handling. Your technical design document must specify the chosen tools, data flows, and transformation logic for every single data object.

Master Data Mapping (The "Single Source of Truth")

This is where most data migration challenges occur. Data mapping is the process of linking a field from the source system to its corresponding field in the new ERP system. For example, your legacy "Cust_Status" field with values 'A', 'I', 'S' (Active, Inactive, Suspended) might map to the new ERP's "Customer Lifecycle" field with values 'Active' and 'On-Hold'. This requires a detailed mapping spreadsheet, approved by business owners, that serves as the "single source of truth" for the migration scripts.

Establish Data Lineage and Approvals

This mapping workbook is your most critical controlled document. It must be stored in a central repository (like SharePoint or Confluence) with strict version control. As you finalize the logic for each data object (e.g., "Customer Master"), that specific tab or section must be formally signed off (digitally or via email) by the designated data owner. This creates an auditable trail of data lineage and accountability, preventing disputes about logic during UAT.

Cleansing and Transforming Data

Never migrate "dirty" data. Cleansing should happen before loading into the new system. This involves de-duplicating records, correcting inaccuracies, standardizing formats (e.g., "USA" vs. "United States"), and enriching incomplete data. Transformation involves converting data to meet the new ERP's requirements, such as splitting a full address field into separate Street, City, and Zip fields. This is often an iterative process run in a staging database, not in your live legacy system.

Conduct Initial Test Loads

Start small. Before building complex scripts for millions of records, manually load a few representative records (e.g., one complex customer, one simple vendor) into a test environment. This "smoke test" quickly validates your mapping logic and assumptions. It helps confirm if data types are correct, if required fields are populated, and if basic business logic in the new ERP (like creating a customer) is successful.

Phase 3: Build, Test, and Validate

This is the "rehearsal" phase. Here, you build the automated scripts, run them in a non-production environment, and rigorously validate the results. The goal is to simulate the final cutover multiple times to identify and fix every possible error, ensuring a predictable and smooth go-live.

Develop and Refine Migration Scripts

Based on your mapping documents, your technical team will develop the automated ETL scripts. These scripts will extract data from the source, apply the cleansing and transformation rules you defined, and load it into the new ERP. These scripts must be version-controlled and thoroughly commented. They should also include robust error logging to capture any records that fail to load and the reason why, so they can be addressed.

Execute Multiple Test Cycles (Unit, System, UAT)

A successful ERP data migration requires several rounds of testing. Start with unit testing (migrating just "Customers") to check basic field-to-field accuracy. Move to system testing (migrating "Customers," "Orders," and "Invoices" together) to check data relationships. Finally, conduct User Acceptance Testing (UAT), where business users interact with the migrated data in the new ERP to confirm it supports their day-to-day processes.

Validate Data Integrity and Performance

Validation goes beyond just checking if the data is loaded. You must prove its integrity. Use reconciliation reports to compare record counts and financial totals (e.g., "Total AR balance in legacy system" must equal "Total AR balance in new ERP"). Set firm KPIs for this phase: for example, a target data defect rate of < 0.5% found during UAT is a common goal. Performance testing is also crucial; your scripts must be able to load the full data volume within the allowed cutover weekend window. A firm KPI here might be: "Full-load data rehearsal must complete in ≤ 36 hours to fit comfortably within a 48-hour cutover window." If your full load takes 72 hours, your migration plan is not viable.

Finalize the Cutover Plan and Rollback Strategy

The cutover plan is a minute-by-minute script for the go-live weekend. It details who does what, when, and how, including pre-migration and post-migration validation steps. Crucially, it must include a rollback plan. Define the "point of no return" and the exact steps required to revert to the legacy system if the migration fails. This plan is your most important insurance policy against a catastrophic failure.

Phase 4: The Cutover and Go-Live

This is the main event where the migration project shifts from testing to production. After months of planning and rehearsal, the team executes the finalized cutover plan. The focus here is on precision, communication, and rapid validation to get the business running on the new ERP system.

The Go/No-Go Decision

This is the final meeting before the cutover begins. This decision requires absolute clarity on roles. The Project/Program Lead typically executes the meeting, the IT/Migration Lead informs on technical readiness, and the Business/Data Owners (e.g., CFO, Head of Operations) hold the final approval authority. The migration team presents the results of the final test cycle and any outstanding critical issues. The business must formally sign off, accepting the quality of the data and giving the "Go" to proceed. If UAT failed or critical data is missing, this is the last chance to make a "No-Go" call and postpone the launch.

Execute the Final Data Cutover

This process typically happens over a weekend to minimize business disruption. The team follows the cutover plan precisely: freeze transactions in the legacy system, run the final data extraction, execute the migration scripts to load data into the production ERP, and perform a final smoke test. Constant communication from the project manager to all stakeholders is essential to keep everyone informed of progress and any immediate issues.

Post-Go-Live Validation and Reconciliation

As soon as the system is live, the work isn't over. The finance team and data owners must immediately perform high-level validation. This includes spot-checking key master data (e.g., "Do our top 10 customers look correct?") and, most importantly, reconciling key financial balances. Verifying that trial balances, open AR, and open AP match the legacy system exactly is a non-negotiable step before allowing users to begin transactions.

Post-Migration: Hypercare and Archiving

The new ERP is live, but the data migration project isn't complete. The immediate post-launch period, known as "hypercare," is critical for resolving user-reported data issues. After a period of stability, you must also formally decommission the old systems to complete the transition.

Monitoring the New ERP System

For the first few weeks, the migration team should be on high alert. Establish a clear "war room" or ticketing process with a defined issue taxonomy: is it a true data defect (e.g., wrong balance), a process/configuration issue (e.g., a setting is wrong), or a user training issue? Set a clear Service Level Agreement (SLA) for critical issues, such as: "Acknowledge all P1 (business-stopping) data issues within 30 minutes, resolve within 4 hours." Users will inevitably find edge-case data issues that were missed during testing; this rapid, structured support builds user confidence in the new system.

Decommissioning and Archiving Legacy Systems

Once the new ERP system is stable (typically after 30-90 days), you must formally decommission the legacy systems. This prevents users from accidentally entering data into the old platform. Before turning them off, take a final, secure backup of the legacy databases for long-term archival. This archival strategy is essential for future audits and regulatory compliance, ensuring you can access historical data for years to come.

ERP Data Migration Best Practices

While the phases above provide the how-to, a successful project also relies on overarching principles. These best practices are the 'guardrails' that keep your migration plan on track from start to finish. Following these rules minimizes risk and prevents common data migration challenges.

Prioritize Business Sign-Off, Not Just IT

Your data owners in Finance, HR, or Operations are the only ones who can truly validate the data's business context. The IT team can confirm if the data moved; the business users confirm if the data is correct. Make formal business sign-off a mandatory gate at the end of Phase 1 (Scope), Phase 2 (Mapping), and Phase 3 (UAT).

Cleanse Data Before You Map It

It is always easier to clean, de-duplicate, and standardize data in a staging environment or even in the legacy system before you begin complex mapping. Moving 'dirty' data into the new ERP structure just makes the transformation logic exponentially more complex. Trying to cleanse during the transformation complicates troubleshooting and compromises data quality.

Rehearse the Cutover (Multiple Times)

Do not let the go-live weekend be the first time you run the entire migration sequence. Your team must execute at least two full-scale dress rehearsals to validate performance, find script errors, and prove your cutover timeline is realistic. A full-volume test is the only way to know if your 20-hour plan will actually take 40 hours.

Build and Test Your Rollback Plan

Hope is not a strategy. Every migration plan needs a detailed, tested rollback plan. Define the specific "point of no return" (e.g., when new transactions are allowed in the new ERP). Document and test the exact steps required to restore the legacy system, just in case a critical, unforeseen error occurs during the final cutover.

ERP Migration Checklist (Quick-View)

Here is a high-level summary of the key actions required, distilled from the phased guide above. Use this as a final review tool with your migration team before you begin the project to ensure no critical steps are missed.

Phase 1: Strategy & Scoping

• Team: Assemble the cross-functional migration team (IT and Business leads).
• Audit: Profile legacy data to identify quality, duplication, and integrity issues.
• Scope: Formally define what data to migrate (e.g., 2 years of history) and what to archive.
• Governance: Set data quality standards and business rules for the new ERP.

Phase 2: Design & Cleansing

• Tools: Select ETL tools and document the technical migration design.
• Mapping: Create and get business sign-off on the source-to-target data mapping documents.
• Cleansing: Execute all data cleansing and standardization in a staging area.
• Test: Perform initial "smoke tests" with small data sets to validate mapping logic.

Phase 3: Testing & Validation

• Scripts: Build, test, and version-control all migration scripts.
• Cycles: Run multiple full-scale test cycles, including System Testing and User Acceptance Testing (UAT).
• Validate: Reconcile record counts and financial totals (e.g., Trial Balance, AR) between test systems.
• Plan: Finalize the detailed, minute-by-minute cutover plan and the rollback plan.

Phase 4: Cutover & Go-Live

• Decision: Hold the formal Go/No-Go meeting with all stakeholders.
• Execute: Freeze legacy systems, back up all data, and run the final migration scripts.
• Reconcile: Perform immediate post-go-live financial and master data validation.
• Support: Initiate the "hypercare" support period for rapid issue resolution.

This checklist structure ensures that you move from high-level strategy to granular technical execution in a logical order. Skipping the early scoping and cleansing steps (Phases 1-2) is the most common reason that migration projects (Phases 3-4) fail, resulting in budget overruns and a chaotic go-live.

Build a Resilient Plan for a Successful ERP Data Migration

A successful data migration is the foundation of your entire ERP project's ROI. Rushing this process or treating it as a simple IT task is the most common reason implementations fail. The difference between success and failure lies in a rigorous, business-led, and test-driven methodology.

The journey from legacy systems to a modern cloud ERP is complex, but it's a necessary step in digital transformation. This process is distinct from the initial ERP vendor selection, as it focuses purely on the integrity and quality of your most valuable asset: your data. A phased approach with clear QA gates, rollback plans, and business-owner sign-offs is the only way to manage the inherent risks.

If your team is preparing for a migration, don't underestimate the complexity. The right partner can provide the methodology and technical expertise to ensure your data arrives clean, complete, and correct.

De-risk your ERP implementation. Talk to a data migration advisor at RubinBrown today.