BUG: Preview & Visual Editor blocked - Vite allowedHosts missing modal.host domain

When using the Preview mode or Visual Editor (Edit button) in the Base44 editor, the page shows a “Blocked request” error instead of rendering the app preview.

EXACT ERROR MESSAGE:

Blocked request. This host (“ta-01kkbc4emf2681s8t90×0v3c9p-5173-64y2vk2k4uxlmm5wu16i5n70g.w.modal.host”) is not allowed. To allow this host, add “ta-01kkbc4emf2681s8t90×0v3c9p-5173-64y2vk2k4uxlmm5wu16i5n70g.w.modal.host” to server.allowedHosts in vite.config.js.

THE PROBLEM:

The Vite dev server used for preview/visual editor does not include the dynamic modal.host subdomain in its allowedHosts configuration. Since vite.config.js is a platform-level file that users cannot edit (only pages/, components/, functions/, entities/, agents/, layout.js, and globals.css are editable), this bug can only be fixed by the Base44 team.

IMPACT:

• Preview mode shows blank/error page

• - Visual Editor (the Edit button for visually selecting elements) does not work at all

• - The Base44 AI assistant also cannot fix this since vite.config.js is outside editable file paths

• - The published live app works fine (this only affects the editor preview)

SUGGESTED FIX:

Add server.allowedHosts = “all” (or a wildcard pattern for *.modal.host) to the platform’s vite.config.js configuration. This is a one-line change:

server: { allowedHosts: “all” }

This issue is reproducible across multiple apps and browsers. Please prioritize this fix as it completely breaks the Preview and Visual Editor workflow.

App: 3 Day CBA App (grow.coacheasily.com)

Browser: Chrome (latest)

Date: March 10, 2026