UI became stuck on “Loading data” screen (complete lockout of HA)

Configuration
1

I had 1 blissful week with Home Assistant until it came crashing down (without me doing anything major ;( )

Issue Summary

  • Running Home Assistant OS on Raspberry Pi (32GB SD card, ~20GB free).
  • System had been running ~1 week without major issues.
  • Attempted a Home Assistant update.
  • After update attempt, UI became stuck on “Loading data” screen.
  • Automations continued to work in the background (lights still respond).
  • http://<ip>:8123/api/ returns 401 Unauthorized (backend responding).
  • Supervisor/Observer shows:
    • Supervisor: Connected
    • Health: Healthy
    • Support: Supported

What I Have Tried

  1. Restarted Home Assistant.
  2. Full power cycle (waited before rebooting).
  3. Cleared browser cache / private mode.
  4. Removed home-assistant_v2.db (recorder DB) — no change.
  5. Reflashed fresh HA OS.
  6. Restored full backup (encrypted, key available).
  7. Restored oldest available backup.
  8. Result after restore: same “Loading data” freeze.

Fresh install without restoring works normally.

This suggests the issue is reproducible from backup and likely configuration-level.

Environment Notes

  • Not disk full (20GB free).
  • No major YAML experimentation that I recall.
  • Possibly installed a small editor-related add-on before update.
  • Dashboard appears to be YAML mode (saw lovelace.map, not JSON lovelace file).
  • No custom HACS-heavy setup.

Concern

At this early stage (only ~1 week in), I am already facing a full rebuild scenario:

  • 20+ devices to reconfigure
  • Renaming rooms and entities again
  • Rebuilding automations
  • Losing history
  • Re-pairing Zigbee if necessary

This raises concern about reliability and update safety.
I’m unsure whether this was caused by something I did, a breaking change, or a migration bug. I would prefer not to rebuild from scratch unless absolutely necessary.

If useful, I can provide:

  • Backup structure contents
  • configuration.yaml
  • List of integrations in use
  • Exact version I updated from/to
2

You didn’t say which Pi but in the console, try ha core rebuild

Post your configuration.yaml file. Please use code tags.

3

What browser are you using? Have you tried a different one?
I have a similar experience with Safari sometimes. Hitting reload a couple times works then. Chrome doesn’t seem to have those issues.

4

There is the Entso-e flu going around. Have you caught it as well?