Acumatica Modern UI Migration - Classic UI Deprecated in 2026 R2

Why Migrate: Classic UI Deprecated in Acumatica 2026 R2

Two separate reasons - either one alone is sufficient to act now:

• Acumatica 2026 R2 formally deprecates Classic UI - it will not receive new features, bug fixes, or support in future versions. Classic UI customizations built before 2025 R2 are affected.
• Chrome and Edge are removing XSLT support - the technology Classic UI depends on for rendering. This may cause Classic UI screens to not render correctly in these browsers.
• Migrating to Modern UI also unlocks AI Studio, anomaly detection, and AcuChat - all Modern UI only features in 2026 R1/R2.

Read our full breakdown of Acumatica 2026 R2 changes →

What the Modern UI Migration Involves

Migrating a Classic UI customization is not a simple upgrade. Each custom screen requires:

• Audit - identify XSLT templates, business event handlers, and graph extensions used
• Rebuild - reconstruct the screen layout using Acumatica's Modern UI ASPX framework and xRP graph architecture
• Port business logic - from Classic UI handlers to Modern UI-compatible graph extensions
• Re-map security - field-level security rules and role-based access controls
• Test - regression test in development environment, then UAT in client test environment
• Deploy - production deployment with rollback plan

How Long You Actually Have

Deprecation is not the same as removal, and the difference is what decides your timeline. Classic UI screens keep loading after 2026 R2. What stops is forward motion: no new features, no bug fixes on Classic-only defects, and no support commitment on screens that break after an upgrade. Every release after 2026 R2 widens the gap between what your customizations do and what the platform assumes they do.

The browser side is the part with a date attached that nobody at Acumatica controls. Classic UI renders through XSLT, and Chrome and Edge are both removing XSLT support. When that lands, affected Classic screens can fail to render regardless of which Acumatica version you are on. A tenant that is fully patched and fully supported can still end up with users looking at a blank screen, because the failure is in the browser rather than in the ERP.

That is why we scope migrations by screen count and complexity rather than by release date. A tenant with six lightly customized screens is a different job from one with forty screens carrying business event handlers and field-level security. Both need to move. Only one of them needs to start this quarter.

What Classic UI Deprecation Means for Your Customizations

The screens most exposed are the ones built before 2025 R2, because they predate the Modern UI framework entirely. Those carry the heaviest rebuild cost: the layout is defined in XSLT templates that have no direct Modern UI equivalent, so the screen is reconstructed rather than converted. Screens built after 2025 R2 usually port with less rework, since the underlying graph extensions already follow current xRP conventions.

Business logic is the part that survives best. Graph extensions, event handlers and DAC customizations mostly carry across, because Modern UI changes the presentation layer rather than the data layer. What needs deliberate attention is anything that reaches into the rendered page - custom JavaScript bound to Classic control IDs, embedded XSLT fragments, and field-level security rules that were mapped against the old layout. Those are rewritten, not moved.

We start every engagement with an audit that inventories your customizations and sorts them into port, rebuild, and retire. The retire pile is usually larger than clients expect. Screens built for a workflow that changed three years ago do not need to be migrated at all, and cutting them is the cheapest part of the project. See what else changed in 2026 R2 →

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