Business Central's next major update, Wave 2 2026, arrives in October. Like every major release, it does not wait for a convenient moment. Once your environment reaches the end of its update window, the new version installs whether or not anyone has reviewed it first.

That is by design. Microsoft built Dynamics 365 Business Central around continuous, automatic updates rather than the multi-year upgrade projects that used to define on-premise ERP systems. According to Microsoft's own documentation on update cycles, there are two major update cycles a year, one in April and one in October, and administrators can only control when the update happens within a fixed window, not whether it happens at all.

For most finance teams, that trade-off works in their favour. Continuous updates mean you are never several versions behind and never facing a disruptive re-implementation. But it also means the burden of readiness sits with you, not with Microsoft. Here is what to check before Wave 2 2026 reaches your environment.

Understand the update timeline, not just the date

Wave 2 does not arrive as a single event on a single day. Microsoft's rollout for each Business Central update runs in defined stages, and knowing where your organisation sits in that cycle changes what you need to do and by when.

The preview period starts about a month before general availability, so around September ahead of an October release. This is when Microsoft makes a preview version available in sandbox environments, letting you test new functionality and check extension compatibility before anything touches production.

The update period itself runs for five calendar months from general availability, giving you until roughly March to schedule the update on your own timetable. After that comes a one-month grace period, during which you can push the update date earlier but no longer later. If an environment still has not updated once the grace period ends, Microsoft moves into an enforced update period, and any extension blocking the update can be automatically uninstalled so the update goes ahead. The underlying data is not deleted, but the functionality stops working until a compatible version is reinstalled.

None of these mechanics are unique to Wave 2 2026, this is how every Business Central major update behaves. It is worth restating clearly, though, because it is the reason "we'll deal with it later" is a weaker plan than it sounds. Later has a deadline attached, and that deadline is not negotiable.

Review your customisations and extensions first

Most small and mid-sized finance teams are not running vanilla Business Central. There is usually a tailored report layout, an approval workflow built around how the business actually signs things off, or a per-tenant extension handling something Microsoft never designed for.

These are exactly the elements most likely to be affected by an automatic update. Microsoft runs a compatibility checker as part of its internal testing before any release, but that only validates the base product, not your customisations. Before Wave 2 lands, a straightforward audit is worth the time:

• List every per-tenant extension and third-party app currently installed in production, not just the ones you remember.
• Check each one against its publisher's stated support for the new version, particularly anything from a smaller or niche ISV rather than a major AppSource publisher.
• Flag anything business-critical for priority testing, such as bank feed connectors, VAT submissions, or industry-specific add-ons.

This is not a task to hand to whoever happens to be free that week. It needs input from someone who knows which extensions the finance team actually relies on day to day, because the admin centre will show you what is installed, not what actually matters to month-end.

Check third-party app compatibility properly

It is tempting to assume an app will be fine because it always has been before. Wave 2 changes underlying platform behaviour as well as visible features, so past compatibility is not a guarantee of future compatibility.

The reliable way to check is to install the extension in a sandbox running the preview version and put it through its normal paces, not just confirm that it opens. If a third-party app comes with a support contract or an ISV partner, this is the point to ask them directly whether they have validated their app against the Wave 2 preview, rather than finding out the hard way once the update has already landed.

Test in a sandbox before the update reaches production

This is the single most effective thing a finance team can do, and it is also the step most often skipped under time pressure.

Microsoft's own guidance is direct on this point: administrators should validate extensions and business-critical processes in a sandbox environment on the preview version before the update reaches production. A sandbox environment costs nothing extra within most subscription tiers and gives you a realistic space to run through the processes that would cause the most damage if they broke without warning, month-end close routines, VAT returns, bank reconciliations, or intercompany postings, whatever your team's actual critical path looks like.

Copying production data into a sandbox and scheduling the update there first, rather than testing only against Microsoft's demo data, gives a far more honest picture of how the update will behave against your real setup.

Brief your finance team properly, not just IT

A surprising number of Wave 2 problems are not technical at all. They are the result of finance staff opening Business Central one morning to a changed screen, a moved button, or a workflow that behaves slightly differently, with no warning that anything was coming.

A short briefing before the update lands solves most of this. It does not need to be exhaustive. It needs to cover what is actually visible to the people doing daily work, when it is happening, and who to contact if something looks wrong. If your organisation has switched on any optional features early through Microsoft's Feature Management settings, that is worth mentioning too, since some changes may already be visible before the main update arrives.

Put a date in the diary now

Eight weeks sounds like plenty of time until it is not. The practical sequence is straightforward: audit your extensions and customisations, confirm third-party app compatibility with your ISV partners, run a full sandbox test against a copy of production data, and brief your finance team on what to expect. Each step tends to take longer than it looks once you actually start it, which is exactly why leaving it until September is the wrong plan.

If you would rather have someone else run this audit properly, Creative Computing offers a Wave 2 readiness check that covers exactly these steps: reviewing your installed extensions, testing your critical processes in a sandbox on the preview version, and flagging anything that needs attention before October. Book a Wave 2 readiness check with our team before the update period begins.