ERP implementation

10 ERP Implementation Mistakes to Avoid

Alex at FitGap

10 Aug 2025 — 2 min read

At FitGap Finance, we help finance teams and business leaders bridge the gap between business needs and ERP functionality — with a focus on Microsoft Dynamics 365 Finance.

ERP projects are high-stakes. Done well, they can transform operations. Done poorly, they drain budgets, stall timelines, and frustrate your best people.

Here are the 10 most common ERP implementation mistakes — and how to avoid them.

1. Unclear Scope

A weak discovery phase creates scope creep and endless reprioritisation.

👉 Also read: ERP Implementation Journey — from design to go-live
https://www.fitgapfinance.com/erp-implementation-journey-design-to-go-live/

Tip: Invest early in a solid Fit/Gap analysis. Clear scope = clear delivery.

2. Relying Too Much on External Consultants

Consultants are essential — but they must not replace internal ownership.

👉 Related: Roles & Responsibilities in an ERP Implementation Project
https://www.fitgapfinance.com/roles-responsibilities-in-an-erp-implementation-project/

Tip: Build a strong internal core team that stays long after go-live.

3. Key Users Not Fully Assigned

Your best people need time and space to drive the project.

👉 Human factor: The Human Side of ERP Projects
https://www.fitgapfinance.com/human-side-erp-projects/

Tip: Backfill their operational workload so they can focus on testing and decisions.

4. Weak Change Management

Resistance is guaranteed.

👉 See also: ERP Governance — roles, escalation & culture
https://www.fitgapfinance.com/erp-governance-roles-escalation-culture-d365/

Tip: Use demos, prototypes, and early involvement to build adoption.

5. Excessive Customizations

Customization = cost + complexity + long-term risk.

👉 Governance lens: ERP Governance vs ERP Management
https://www.fitgapfinance.com/erp-governance-vs-management/

Tip: Push back on customizations and maximise standard D365 functionality.

6. Analysis Paralysis

Workshops drag on forever if users don't touch the system.

👉 Get moving: D365 FO Structure — Beginner’s Guide
https://www.fitgapfinance.com/d365-fo-structure-beginners-guide/

Tip: Let users test early. Real feedback only comes from real usage.

7. Delaying Data Migration

Data migration is the number one bottleneck in ERP projects.

👉 Critical read: ERP Data Migration Traps
https://www.fitgapfinance.com/erp-data-migration-traps/

Tip: Start early with master data, cleanse aggressively, validate constantly.

8. Leaving Security Roles to the End

Security is governance, not an afterthought.

👉 Must read: New User Security Governance in D365 Finance
https://www.fitgapfinance.com/d365-finance-security-10-things/

👉 And: SoD Risks & Audit Conflicts in D365 Finance
https://www.fitgapfinance.com/d365-finance-sod-risks-audit/

Tip: Identify risks early and refine roles continuously post-go-live.

9. Poor Testing Practices

Testing must be realistic and cross-functional.

👉 Environment planning: ERP Environments Needed for an Implementation
https://www.fitgapfinance.com/erp-implementation-environment-strategy/

Tip: Test end-to-end scenarios, not isolated screens.

10. Skipping Dry-Runs and Parallel Runs

Go-lives fail when teams don’t rehearse.

👉 Essential: D365 Finance Cutover Rehearsal Playbook
https://www.fitgapfinance.com/d365-finance-cutover-rehearsal-playbook/

Tip: Always run at least one full dress rehearsal before go-live.

Summary

ERP success depends far more on people, process, and discipline than on technology. Avoiding these pitfalls saves months of rework and prevents budget overruns.

👉 Also read: Real-Life ERP Implementation Lessons
https://www.fitgapfinance.com/real-life-erp-implementation-lessons/