Business Central 14 support has ended: rewrite C/AL as AL extensions, or move to ERPNext?

Who this guide is for

This guide is for owners, finance directors and IT managers at UK and US small and mid-sized businesses running Business Central on-premises version 14 (Spring 2019), usually after an upgrade from Dynamics NAV, with C/AL customisations built over many years: changed posting routines, extra fields on every card, custom reports and integrations.

We implement ERPNext. We also tell BC 14 customers when staying with Business Central is the better answer, and we say where below. If you are still on NAV 2017 or NAV 2018, our NAV 2017 guide and NAV 2018 guide cover the same decision from an earlier starting point. The legacy ERP end-of-support hub lists every vendor date we have confirmed.

Sources, checked on Nov 15, 2026: the Microsoft Lifecycle: Business Central on-premises (Fixed Policy) page, Microsoft’s supported upgrade paths to Business Central, Microsoft’s Txt2Al conversion tool documentation, Microsoft’s guide to upgrading a customised version 14 application to version 25, Microsoft’s on-premises to Business Central online migration overview, Microsoft’s Business Central 14 reimplementation tool (preview) documentation, the Business Central pricing page (US) and Business Central pricing page (UK), the Frappe Cloud pricing page, the ERPNext repository on GitHub and the ERPNext and Frappe documentation linked below.

What Microsoft’s lifecycle page shows

Microsoft shows these dates as timestamps (for example 10/15/2025 6:59:59 AM). To avoid an off-by-one-day error we describe the end as October 2025. Either way, version 14 has been out of support for over a year.

Microsoft’s Txt2Al documentation adds the fact that shapes everything else: version 14 is “the last version to support C/AL”. The Txt2Al conversion tool ships only with version 14, and it is no longer available from version 21 (2022 release wave 2).

Why being out of support on BC 14 matters

• No more updates for version 14. Any security fix or regulatory change needed after the end date is yours to build and test. In the UK that includes changes affecting VAT and Making Tax Digital submissions; in the US, anything your sales tax or 1099 processes need.
• The upgrade path is getting longer. Microsoft says that from 2025 release wave 1 (v26) a direct upgrade from version 14 to the latest release is not supported; you go through 2024 release wave 2 (v25) first, then to the current release.
• The C/AL skills pool shrinks every year. The developers who know C/SIDE are moving to AL or retiring, and the conversion tools are tied to version 14 media.
• Your platform ages with it. Check the lifecycle of the Windows Server and SQL Server versions under your BC 14 install too.

The key point for planning: there is no “small” upgrade from BC 14. Moving to any supported Business Central release means converting C/AL to AL. So the real decision is not “upgrade or migrate”; it is “rebuild in AL or rebuild in ERPNext”.

Path 1: convert C/AL to AL extensions and upgrade Business Central

Microsoft’s guide to upgrading a customised version 14 application describes the work in two parts:

• Application upgrade. Your code moves from C/AL in the base application to AL extensions. You create several extensions, some used only for the upgrade. Txt2Al converts exported C/AL objects to AL syntax as a starting point; the output then needs refactoring, because modern AL extensions add to Microsoft’s base objects through table and page extensions and event subscribers rather than by editing base code.
• Data upgrade. Data moves from your current tables to extension-based tables in two phases, using a table migration extension, the destinationappsformigration server setting and a migration.json file.
• User personalisation is lost. Microsoft says user personalisation and profile customisations done in the Windows client are lost after upgrade; page customisations must be recreated in the current client or as AL extensions.
• Two hops. Version 14 to version 25, then on to version 29 (2026 release wave 2), per the supported upgrade paths page.

Plan for what comes after the upgrade too. Business Central ships two major releases a year, release wave 1 and release wave 2, as the version names on Microsoft’s upgrade paths page show. On-premises, keeping current is your project each time; online, Microsoft applies the updates and you test your extensions against them. Either way, AL extensions that follow Microsoft’s extension model are what make those regular updates manageable, which is the point of the whole conversion.

You can stay on-premises after the upgrade or move to Business Central online. The online move uses Microsoft’s cloud migration through Azure Data Factory, with your on-premises system remaining the live environment until migration completes.

The BC 14 reimplementation tool

Microsoft also documents a Business Central 14 reimplementation tool for customers who want a fresh start online. It migrates essential data only: masters (customers, vendors, items, G/L accounts, dimensions), open sales and purchase orders, opening balances and setup data, plus a defined subset of posted history. Legacy C/AL customisations and their data are not migrated. Microsoft labels it prerelease documentation and a preview feature that is “not meant for production use”, so check its status before you plan around it. Note what it tells you: even Microsoft’s own clean-start route assumes you rebuild customisations.

Path 2: reimplement on ERPNext

ERPNext is an open-source ERP (GPL-3.0) on the Frappe framework. Moving from BC 14 is a reimplementation: you migrate masters, open items and balances, and rebuild the customisations you still need with these tools:

Standard ERPNext covers the core BC 14 areas most SMBs use: general ledger with cost centres and ERPNext accounting dimensions documentation, sales and purchase cycles, inventory with warehouses, batches and serial numbers, ERPNext Pricing Rule documentation, BOMs and work orders (ERPNext Bill of Materials documentation, ERPNext Work Order documentation), projects and fixed assets (ERPNext Asset documentation). Data comes in through ERPNext Data Import documentation, the ERPNext Chart of Accounts documentation importer, ERPNext opening balance documentation and ERPNext Stock Reconciliation documentation.

What ERPNext does not give you: Business Central’s Microsoft 365 and Power Platform integration, the AppSource partner ecosystem, and Microsoft-maintained localisations. For UK VAT and Making Tax Digital, or US sales tax, test your exact filing process in the pilot; do not assume.

Comparing the effort: a method, not a guess

Both paths rebuild customisations, so size them the same way. Export your C/AL object list (objects in the customer ID range plus modified standard objects) and classify each one:

Count the rows that land in “refactor” or “rewrite”. If they are few, the AL path is usually cheaper and keeps your history and your team’s Business Central skills. If they are many, both paths are effectively new builds and the licence difference and product fit should decide.

Four mistakes we see on BC 14 projects

• Treating Txt2Al output as finished. Converted syntax is not a working extension. Budget for refactoring, testing and new automated tests on either path.
• Converting everything. Many C/AL objects were written for NAV versions that lacked features current Business Central and ERPNext have as standard. Retire them rather than port them.
• Forgetting the user layer. Microsoft warns that Windows-client personalisation and profile customisations are lost on upgrade. Users notice this on day one; plan role centres or workspaces and training early.
• Leaving history to the end. Decide in week one how auditors and staff will see BC 14 history after go-live: a read-only BC 14 instance, a reporting database, or (on the AL path) the upgraded data itself.

Licence costs: official prices in USD and GBP

Prices are paid yearly, checked on Nov 15, 2026. A worked example at list price for full users (add Team Members for light users):

These are list price × users × 12 from Microsoft’s pages. They exclude the AL conversion, implementation, partner support and any discounts.

Frappe Cloud publishes USD prices: site plans from $5 a month (about £3.78) and servers from $40 a month (about £30.22), checked on Nov 15, 2026. The GBP figures are indicative conversions, not Frappe prices.

Indicative GBP conversions use the Bank of England daily spot rate (series XUDLUSS) of US$1.3238 per £1 for 12 Nov 2026, the latest published figure when we checked on Nov 15, 2026. They are not official UK prices: the vendor does not publish a GBP list price for these items, and your invoice currency, rate and VAT treatment may differ.

Where staying with Business Central is the better answer

• Your C/AL customisations are light: mostly fields, pages and reports. The AL conversion is then a contained project and you keep your history and know-how.
• Your business runs on Microsoft 365, Power BI and Power Automate and you value BC’s native integration with them.
• You depend on AppSource apps or an ISV vertical built on Business Central.
• You want Microsoft-maintained UK or US localisation and a large partner market.

ERPNext is the better fit when your customisations are heavy enough that AL is a rewrite anyway, per-user licences are a large share of cost, you want open source you can self-host or run on Frappe Cloud, and your processes fit ERPNext’s standard modules after the fit test.

A practical plan for BC 14 sites

Decision table

Best for, and wrong choice when

Frequently asked questions

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