Bedrock Editor Mode 1.26.60: Existing project loads with missing UI buttons and scripting errors

Short description of the issue

After updating Minecraft Bedrock Editor to version 26.60 on October 28, 2026, an existing project that previously worked correctly began loading with many missing Editor UI buttons and partially initialized panels. The content log reports internal scripting errors in _PrefabLayoutBehavior, addButton, and createPayload, followed by a Watchdog hang warning.

Steps to reproduce

1. Open Minecraft Bedrock Editor version 1.26.60 on Windows.

2. Load an existing project created in an earlier version of the Editor. The affected project has been under development since approximately June 2026.

3. Enable the content log and observe the Editor initialization process.

4. Check the Editor interface and observe whether all buttons and panels load correctly.

5. Create a new project using the same installation and the same custom resource pack and behavior pack as the affected project.

6. Open the new project and compare its Editor interface and content log with those of the existing project.

Expected result

Both existing and newly created projects should load the Editor interface correctly, with all expected buttons and panels available and without internal scripting errors or Watchdog hang warnings.

Actual result

The existing project loads with many missing Editor buttons and partially initialized UI panels, making it very difficult to continue working on the map.

The content log reports the following errors:

[Scripting][error]-[resourcePack.editor.server.name] InternalError: interrupted
    at addButton (@minecraft/server-editor:2)
    at addButton (@minecraft/server-editor)
    at _PrefabLayoutBehavior (Main.js:48591)
    at <anonymous> (Main.js:62829)
    at onLifecycleEvent (@minecraft/server-editor:2)
    at <anonymous> (@minecraft/server-editor:2)

[Scripting][error]-[resourcePack.editor.server.name] InternalError: interrupted
    at createPayload (@minecraft/server-editor:2)
    at <anonymous> (@minecraft/server-editor)
    at map (native)
    at createPropertyItemPayloadList (@minecraft/server-editor)
    at createPropertyItemPayloadList (@minecraft/server-editor)
    at createPanePayload (@minecraft/server-editor:2)
    at createPayloads (@minecraft/server-editor:2)
    at createPayloads (@minecraft/server-editor:2)
    at <anonymous> (@minecraft/server-editor:2)

[Scripting][error]-[Watchdog] 10843 ms hang detected in 'resourcePack.editor.server.name'

The same installation loads a newly created project correctly, with all Editor buttons visible and functioning as expected. The new project also uses the same custom resource pack and behavior pack as the affected project.

The issue therefore appears to be specific to the existing project or its stored data, rather than being caused solely by the custom packs. The exact cause is unknown.

Additional information

• Platform: Windows.

• Minecraft Bedrock Editor version: 1.26.60.

• Date first observed: October 28, 2026.

• The affected project worked correctly before updating to version 1.26.60.

• The project has been under development since approximately June 2026 and may have been carried forward through several Editor versions.

• The project uses custom resource and behavior packs created for the map.

• Both packs work correctly in a newly created project using the same Editor installation.

• The content log was enabled when the errors occurred.

• Three screenshots are available: one showing the working Editor interface in the new project, one showing the missing buttons in the affected project, and one showing the scripting errors in the content log.

• It has not yet been established whether the problem is caused by legacy project data, an Editor initialization issue, or another compatibility problem.

The issue significantly impacts the usability of the existing project and prevents normal map development. Any guidance on diagnosing or recovering the affected project would be appreciated.