Frequent "Reload UI" after upgrade to 2025.11.1

[Masterz69]

Checklist

• I have updated to the latest available Home Assistant version.
• I have cleared the cache of my browser.
• I have tried a different browser to see if it is related to my browser.
• I have tried reproducing the issue in safe mode to rule out problems with unsupported custom resources.

Describe the issue you are experiencing

When navigating to another dashboard/lovelace - "Reload UI" appears instead of contents.
That happend in Chrome. Using Edge - "Error" appears on views buttons.
Never saw this behaviuor before 2025.11.1 HA Core version.

Describe the behavior you expected

Dashboard contents to be dispalyed.

Steps to reproduce the issue

No steps, just installed 2025.11.1 over 2025.10.3.

What version of Home Assistant Core has the issue?

2025.11.1

What was the last working version of Home Assistant Core?

2025.10.3

In which browser are you experiencing the issue?

Chrome 142.0.744461, Edge 142.0.3595.53

Which operating system are you using to run this browser?

Windows 10

State of relevant entities

Problem-relevant frontend configuration

JavaScript errors shown in your browser console/inspector

Additional information

No response

[Aadje3]

Same here!

Description of the Issue

Over the last weeks I’ve been experiencing recurring frontend freezes after making changes to YAML templates, dashboards, or configuration files. When certain template errors or duplicate unique IDs occur, Home Assistant does not gracefully recover and instead enters a broken state where the frontend refuses to load.

This happens even with relatively small or harmless changes.

Symptoms:
Home Assistant hangs during startup, repeating the same log messages
The UI becomes completely inaccessible (both default and YAML dashboards)
Safe mode sometimes loads, but often the UI still does not respond
Template validation errors or duplicated unique IDs cause the entire frontend to fail
Some .storage files or dashboard YAML files appear to become partially written or corrupted
HA refuses to progress past the frontend initialization stage
The only recovery is manual file restoration.

System Setup:
Home Assistant OS running inside a VM on Synology DS224+
VM resources: 4 cores, 8–18 GB RAM

All configuration managed through /config using File Editor / external tools
Large amount of templates and dashboards, all YAML-based
Using recent HA versions (2025.10+ / 2025.11)

Steps to Reproduce (Typical Scenario)
Edit or update a YAML template file (e.g., adding sensors or modifying Jinja)

Restart Home Assistant
HA begins startup but stops progressing during the frontend load
The UI never appears; logs repeat the same few lines

Only way out is to manually replace or repair files in /config, or revert to a backup
Not every change triggers the freeze, but once HA gets into this state, it never self-recovers.

Expected Behavior:
A template or dashboard error should be isolated
The frontend should still load (even in “safe mode”)
HA should show the error in UI or logs without blocking the entire system
No need for manual recovery of .storage files or dashboard YAML

Actual Behavior:
A single faulty template can cascade into a full frontend crash
HA gets stuck during UI initialization
The system cannot auto-repair corrupted .storage entries
Only manual file recovery or restoring a backup works

Additional Notes:
This behavior makes it difficult and risky to develop dashboards or templates.
It feels like the frontend is too fragile and tightly coupled to template validation.