Ask any finance team running Microsoft Dynamics GP (Great Plains) what worries them most about moving to Business Central, and the answer is rarely the data. It is the customizations.
Over ten or twenty years, most Dynamics GP systems collect a long list of changes: Dexterity modifications, extra fields added with Modifier, VBA scripts, .NET add-ins, custom reports, SQL triggers and a handful of third-party products. Each one solved a real problem at the time. Many are now so familiar that nobody remembers they are not part of standard Dynamics GP.
The important thing to recognize is this: none of these customizations move to Business Central automatically. Each one needs a decision. In this article, we will explain the main types of Dynamics GP customization, how Business Central handles change differently, and a practical way to map each item to its new home.
Why Dynamics GP Customizations Cannot Simply Be Copied
Dynamics GP and Business Central are built on completely different technology.
Dynamics GP customizations are mainly written in Dexterity, Dynamics GP’s own development language, with additional tools such as Modifier, VBA, Visual Studio Tools and direct SQL objects. Many of them change or sit very close to the core product.
Business Central is changed through extensions, written in a language called AL. Extensions sit alongside the standard product and connect to it through published events. They do not change Microsoft’s base code.
This “extensions only” approach is the main reason Business Central can be updated by Microsoft twice a year without breaking your system. It is also why every Dynamics GP customization must be rethought, not converted line by line.
The Types of Dynamics GP Customization You Will Find
Before planning anything, build a complete inventory. In our experience, most Dynamics GP systems contain several of the following:
| Dynamics GP customization type | What it usually does |
|---|---|
| Dexterity customizations | New windows, extra validation, changed posting logic, custom tables |
| Modifier changes | Moved, hidden or added fields on standard windows |
| VBA scripts | Field defaults, warnings, simple automation |
| Visual Studio Tools (.NET) add-ins | Integrations, extra windows, business rules |
| Extender | User-defined fields and windows without coding |
| SQL objects | Triggers, stored procedures, views and scheduled jobs |
| Report changes | Report Writer modifications, Word templates, SSRS reports |
| Integrations | eConnect, Integration Manager and SmartConnect jobs |
| Third-party (ISV) add-ons | Payments, payroll, multi-entity, document management, sales tax and more |
Do not forget the less visible items: SQL jobs, scheduled integrations and Excel reports that read Dynamics GP tables directly. These often break quietly after a migration if nobody listed them.
How Business Central Handles Change
Business Central offers several ways to meet a requirement, and choosing the right one matters more than the code itself:
- Standard functionality: Business Central includes a great deal that needed customization in Dynamics GP, such as dimensions, approvals, deferrals, item tracking, warehouse processes and multiple languages.
- Personalization and configuration: users and administrators can hide fields, rearrange pages and set up defaults without any development.
- AppSource apps: ready-made extensions from Microsoft partners, installed and licensed like any other app.
- Per-tenant extensions: custom AL extensions built specifically for your organization.
- Power Platform: Power Automate, Power Apps and Power BI for workflows, small applications and reporting around Business Central.
- Report layouts: Word, Excel and RDLC layouts for documents and reports.
You can read more about how these work on our Business Central extensions page.
The Five Possible Outcomes for Each Item
For every customization and add-on on your list, there are five possible outcomes. We would emphasize going through them in this order, because each step down costs more to build and to maintain.
1. Retire It
Ask honestly whether the customization is still used. Processes change, staff move on, and some modifications have done nothing for years. Usage logs, SmartLists and conversations with users quickly reveal these. Retiring them is the cheapest result of all.
2. Replace It with Standard Business Central
Many common Dynamics GP customizations exist as standard features in Business Central. Typical examples include:
- Extra fields for reporting → dimensions
- Custom approval windows → standard approval workflows
- Default values set with VBA → templates and setup defaults
- Custom document layouts → Word or Excel report layouts
- Extender user-defined fields → often dimensions or standard fields
Our Business Central features page gives an overview of what is available out of the box.
3. Use an AppSource App
If the need is common across many businesses, there is usually an app already. Many established Dynamics GP ISVs have released Business Central versions of their products, and AppSource offers thousands of other apps for payments, banking, sales tax, document capture, multi-entity management, EDI and more.
When reviewing apps, check:
- Whether it covers your actual process, not just the headline feature
- The license model, usually per user or per company, per month
- The vendor’s support, update record and customer references
- Whether it is available in your country and Business Central version
4. Use the Power Platform
Some Dynamics GP customizations are really workflows or small side applications: a notification email, an approval outside the finance team, or a form for warehouse staff. These often fit Power Automate or Power Apps better than a full extension, and can be maintained by a wider group of people.
5. Build a Custom Extension
What remains, the requirements that are genuinely unique to your business and give you a real advantage, is built as a per-tenant AL extension. This is often a much shorter list than people expect.
Good extension design keeps logic separate from the standard product, uses Microsoft’s published events, and is fully documented. That way, it continues to work through Business Central’s regular updates.
Mapping Dynamics GP Add-Ons
Third-party products deserve particular attention, because they often hold their own data and processes. For each one:
- Contact the vendor: Ask whether there is a Business Central version, and whether they provide a migration path or tools.
- Compare the functionality: The Business Central version may work differently from the Dynamics GP product you know.
- Review the data: Decide which data must move, and whether it fits standard Business Central tables, the vendor’s extension tables, or an archive.
- Check the cost: Your Dynamics GP add-on licenses do not normally carry over, so budget for new subscriptions.
If there is no Business Central version, look for an alternative AppSource app or consider whether standard features now cover the need.
What Happens to the Customization Data?
Custom tables in Dynamics GP often hold valuable information: extra customer attributes, contract details, approval history and so on. Microsoft’s cloud migration tool moves standard Dynamics GP data, but custom table data needs a plan.
The usual options are:
- Map it to extension tables in Business Central. Once your extension creates matching tables, the cloud migration tool can be configured to copy data into them using table mappings.
- Import it after go-live using configuration packages or an integration tool.
- Archive it, keeping it available for reference without bringing it into the live system.
Our article on what data migrates from Dynamics GP to Business Central explains the wider data picture.
A Practical Mapping Template
A simple register keeps the whole exercise organized. For each item, record:
| Column | Example |
|---|---|
| Item | Dexterity: extra credit check on sales orders |
| Type | Dexterity customization |
| Business purpose | Stop orders for customers over credit limit |
| Still needed? | Yes |
| Business Central option | Standard credit limit warning + approval workflow |
| Outcome | Replace with standard |
| Data to migrate | None |
| Owner | Credit control manager |
| Effort estimate | Low |
Analyzing every item in this format gives you a clear scope, a realistic budget and a sensible order of work. It also helps business owners make decisions, rather than leaving everything to the technical team.
Common Mistakes to Avoid
- Rebuilding everything “as it was”: This brings old workarounds into a new system and greatly increases cost.
- Leaving the review until late in the project: Customizations drive scope, cost and timeline. Review them first.
- Ignoring reports and integrations: These are customizations too, and often the most numerous.
- Forgetting ongoing costs: AppSource apps and extensions have subscription or maintenance costs that should be in your budget.
- No documentation: Every extension you build should be documented and kept in source control.
How Nevas Technologies Can Help
Nevas Technologies has worked with Dynamics GP since version 7.0, including extensive Dexterity and integration work, and builds Business Central extensions for clients across the USA and Asia Pacific. We can:
- Produce a complete inventory and mapping of your Dynamics GP customizations and add-ons
- Recommend the right outcome for each item, with realistic effort estimates
- Build and support AL extensions, and select suitable AppSource apps
- Deliver your full Dynamics GP to Business Central migration and Business Central implementation
- Keep your current system stable through Dynamics GP support until go-live
- Advise on design with our experienced Business Central consultants
Summarizing the Key Points
- Dynamics GP customizations do not migrate automatically. Each needs a decision.
- Start with a full inventory, including reports, SQL objects, integrations and ISV add-ons.
- Work through five outcomes in order: retire, standard feature, AppSource app, Power Platform, custom extension.
- Plan the data held in custom tables: map, import or archive.
- Budget for ongoing costs of apps and extensions.
Handled well, the move to Business Central is a chance to remove years of complexity and keep only the customization that truly adds value.
If you would like a customization review of your Dynamics GP system, contact Nevas Technologies or schedule a demo with our Business Central team.
Frequently Asked Questions
Can Dexterity code be converted to Business Central? No. Dexterity and Business Central’s AL language are completely different. The business requirement is rebuilt, not the code converted.
Do Dynamics GP add-ons work in Business Central? Not directly. Many vendors offer separate Business Central versions, and AppSource has alternatives for most common needs.
Will my custom table data migrate? Only with planning. It can be mapped to extension tables, imported after go-live, or archived.
How much customization will we need in Business Central? Usually far less than in Dynamics GP, because many former customizations are now standard features or available as apps.
